Help getting T2 swap/rebuild to run
 

Hey everyone,

I've been working on a t2 swap and build for the last few months and finally got to the point where it was time to start it. It did start, but then promptly died. I've been tweaking things over the last few days with little luck, and I think its time i ask for help.

Its mildly built, but I'm going to list everything that i think could matter.

- Rebuilt S4 T2 swap into S4 NA Chassis using NA harness
- Street ported
- Emissions delete and throttle body mod
- 3 inch TBE
- Rewired Fuel Pump
- FPD delete
- Aeromotive Stealth 340 pump
- SAFC2

Alright i think thats everything that could possibly have a part of my symptoms.

So whats been happening is it will start and then promptly die and then if i try to start it again it will be flooded. I then have to pull power to the pump and then crank it over and then it will start with the fuel thats in the line. At this point if i just let it run with the fuel in the line it revs up to about 4k on its own but smoothly and then dies after it runs out of fuel. If i plug the pump in while its revving up it will then try to die. I can catch it before it dies but it runs terribly and backfires a lot. It also has about 55 psi of fuel pressure during this time according to my fuel pressure gauge. My afr gauge reads about 14.6 as well but i doubt the reading is accurate.

Things I've done:

Quadruple checked timing
Checked all my vacuum hoses for leaks.
Checked TPS and idle scew settings. The TPS was done on a cold engine though so i dont know how accurate that can be.
Tried to tune it a bit with the safc. It seems like its getting too much fuel but pulling fuel didnt do anything.

Thats about it. I feel like its getting too much fuel based on the high fuel pressure when its running but I'm not sure if that would cause it to run so poorly. So i would love any input on 1. Why is it unable to run well or at all really? And to a lesser extent 2. Why is it revving so high on start up when its just running off the fuel in the lines?

Glad to hear that you're getting somewhere. I would say you're thinking correctly. Your fuel pressure is too high. 55?! Way too high. Stock line pressure is 36-37lbs.

Get an adjustable FPR and set it to 36-37psi.

If you can get it to idle low enough throw a timing light on it and see where you're at.

Yeah I was worried that was going to be the case. I didn't want to have to drill and tap my fuel rail to accept an AN fitting. Unless anyone knows of a more bolt on solution for an aftermarket fpr?

I know that the thread specs are hard to match for the s4 rail. It's a strange size and its metric. You might be able to find something if you look hard enough or maybe have an adapter made. I'm running s5 so I had to change the whole rail.

you shouldn't need to. there's a diagram of the fuel system around (i think it was RETed's site, if i recall) that said the thread size and pitch you need. i was able to get all the fittings for it shopping between Pegasus Racing and Summit Racing. i don't think it was all that expensive either.

https://www.pegasusautoracing.com/

https://www.summitracing.com/

So my options are to tap new common threads or go aftermarket rails. Given a choice between the two I think I'll mod my stock rails. One day when I go to a bigger turbo I may go aftermarket rails and convert to a parallel fuel system, but I think that's pretty overkill for my modest amount of power.

Well I appreciate the response and I'll update this thread once I get the new fpr on.

Oh dang thanks for the heads up. Are you referring to his parallel fuel system picture? According to that pic it's a M12x1.25 thread.

https://cimg3.ibsrv.net/gimg/www.rx7...ce4fcedece.jpg

unless i missed something, this is not true.

FC3S Pro v2.0: Mods - Fuel System

in the diagram where it shows how to convert to a parallel system, it shows you need:

m12 x 1.25 to -6 an adapters (x2)
m14 x 1.25 to -6 an adapters (x2)

they swap out with your stock fittings - you literally unscrew and replace. no fuss (thread tape and washers aside). you may need to replace one of them with a plug depending on your regulator, but that's about it.

to attach your rails to the regulator and the supply and return lines, you can use -6 an Push-lock or straight adapters. you'll just have figure out what angles you need.
______________________________________

EDIT:
Sorry. your last post was not there when i started typing my response. :) yes, that's the diagram.

Any recommendations on the fpr? Was looking at the aeromotive a1000 because it seems like a popular choice. Only goes as low as 40 psi though. Should be good enough right?

EDIT: Actually that would mean 40 psi would be the pressure at idle which is no where good enough.

Update on the car:

I just finished installing a 30-70 psi adjustable aeromotive FPR. My fuel pressure is now in a much better spot, but I'm still getting the same symptoms as i did before. Car still floods with the pump having power but will start and sound fine with the pump off. Still can plug the pump back in before it runs out of fuel but like before it will still try to die immediately unless i catch it and then will run terribly and back fire a lot.

So it doesn't look like the FPR was the problem, though it does sound a little better now with the pressure at a more stock level. I'm still of the believe that it is fuel related because otherwise it wouldn't run smoothly with the pump turned off. It has to be the pump then right? I'm starting to wonder if i should get something more stockish like an FD fuel pump and save the aeromotive 340 for when I'm making bigger power.

Anyone have any thoughts on this?

What is your line pressure? Is it timed correctly? Hard to tell but when I hear backfiring I think timing.

When i got it started and kept it alive for a few seconds pressure was about 37 psi. I've checked timing 4 times now. Lining up the indent on the gear to the fin on the shaft while the timing pin points to the first (right) timing mark.

I guess whats messing with me is that the car starts, revs to about 4k and sounds good while the pump is turned off. So i feel like it has to be pump related if everything else seems to be running like its supposed to for those few seconds that it runs with the pump off.

Are you doing your pressure test with key in ON position with engine not running?

It's 37 psi with the car running. It's about 25 if I prime the pump with the car off.

have you tried just ignoring the gauge and turning it down more to see if you can get it to behave right?

I have. Tried turning it as low as it'll go but it doesnt seem to change much.

I also started going through the electrical system a bit and checking resistances and such. The CAS checked out fine, trailing coil checked out, but the leading coil was under .1 ohm so that is certainly under spec. Tried cleaning the contacts and grounds and that didn't help. I dont think thats the issue main issue here because it still is obviously working fine with the way it runs when it starts with the pump off, but still probably needs to be replaced.

Tomorrow I'm going to move onto checking the MAF. I've read about bad MAFs displaying some of the symptoms that im having.

well, i don't know anything about the S-AFC IIs, so i will be useless there, but maybe there's some kind of adjustment that could be made in there to help??? i don't know. just spit-balling.

also, how did you re-wire the pump? specifically, what's controlling the output? i suppose this may possibly all boil down to pump overkill. the idea you mentioned about trying a more stock pump seems like it might be worth a try. it doesn't sound like you have any really crazy mods (yet), so a more "stock" pump will be fine.

Yeah i may end up trying to find a used t2 pump just to see what that does eventually. I still want to dig around some more first to see if its something else before throwing more money at it.

Here is the schematic i used for the fuel pump rewire.
https://www.rx7club.com/attachments/...mprewire-1.jpg

It's strange that you're reading higher pressure while running. You should be seeing opposite behaviour. Faulty readings? Return line plugged? Bad regulator?

I guess anything is possible. I'd be surprised if the new fpr was bad right out of the box. The return line is an interesting idea though. I'm actually starting to wonder if it's possible I have the hoses backwards at the tank. Going to pull the return line from the fpr when I get home and see where the fuel comes from. If that turns out ok then I'll pull the return line at the tank and see if it's getting good flow.

Aside from that im going to switch the primary and secondary injectors. I was testing the primaries a few weeks ago by giving them direct battery voltage and I guess that could have hurt them. Didn't do that to the secondaries though.

Does the fuel system hold pressure after you cut power to the pump?
What ECU are you running and how confident in your harness modification? You may want to remove the SAFC for troubleshooting.
I've run a walbro on a stock FPR that hit about 50 psi, but it still started and idled fine. A little stinky, but fine.

High revs are a vacuum leak or the throttle butterflies aren't adjusted correctly. Higher revs should help keeping it running while you troubleshoot, so attack that second.

The system does maintain its pressure after everything is turned off. Now that I think about it I've read that people who have an aftermarket fpr tend to have their fuel drain back fairly quickly.

Im running an rtek 1.5 s4 t2 ecu.

As far as the harness is concerned I guess im 50/50 on it. The PO of this engine did the harness modifications so I can't be sure it's done well, but he did run the engine himself for awhile until he blew a coolant hose and overheated it.

That's a good point on the safc too. Might be best to start removing unneeded things for simplicity sake if I don't find what's going on soon

BIG UPDATE: I got the car to idle! Well kind of. I propped the maf open and started it. It would rev up and down between 1k and 1.5k rpm. This is the first time it's stayed alive without my intervention. What does it mean though is my next question.

I would keep focusing on your fuel system.

IF you did your fuel pressure test correctly and your readings are indeed correct then you DEFINITELY have a fuel issue. I would also disable the fuel controller as someone mentioned just until you sort this out.

Your fuel pressure while running should be about 8-10 psi lower than when it's not running. I would check return line and line configuration.

Where are you T'ing into for the pressure test? Or do you have a fuel gauge?

I have a fuel pressure gauge that is currently Tee'd in between the filter and primary rail. I will remove the power wire to the safc tomorrow. Any thoughts on why it would sort of run with the MAF propped open though?

Also I did check all the hoses and they are hooked up correctly and the return line flows well. Still could try switching the injectors if removing the safc doesn't help.

I'm still trying to figure out why you're reading higher pressure when running -there is vacuum present which should drop your pressure pound per pound. If you are running 37lbs when running that puts you almost 10lbs over your mark which is pretty rich.

If your FPR is working properly then, while idling, you should see the pressure increase but 8 or so lbs(iirc) when the vac line is disconnected from FPR(use thumb on vac line to prevent vac leak and confirm that you actually have vacuum present at that line). However, even with your line not working you should still only read what you read when it's not running which in your case would be 25psi. Strange.

Or you have a clogged/kinked line. I can't see anything else causing this issue. Unless you have a setting that is incorrect in which case I can't help you :/.

Hmmm the vacuum port im using certainly could be clogged. I'll have to pull the UIM and try and clean it. Im using a nipple on the LIM for my vacuum source for the fpr. I'll also make sure the vacuum hose isn't getting kinked or crushed.

Though I don't think this is a vacuum thing. When I set the static pressure it shouldn't go up unless I'm on boost right? It could and should go down with vacuum but the only way it should go up is with boost or at least that's how I understand it. Think something like a primary not injecting could cause the higher fuel pressure?

Anyway, I guess I have a little list of things to do over the week.

Thinking on it more, the SAFC cannot control pressure, at least I don't imagine that it can, so it's not the issue but disabling it could still prove useful.

Honestly, it has to be one of these things: bad gauge, clogged line, bad FPR. A bad gauge is probably the most annoying of these so hopefully it's good.

Logically these are your problems/solutions:

Problem
You test your "line pressure" and you get 25psi. It should be at 36-37. This is a problem which can only be fixed by adjusting FPR.

Solution
Adjust FPR to 36-37.

Problem
When you start the car your fuel pressure rises to 37psi. It should be at 30ish. This is caused by two things. A bad FPR or a clogged return line.

Solution
Replace FPR or clean/replace clogged return.

Is there any chance that you may have purchased a fuel regulator that is too small? Hmm, unlikely. Maybe your return is too small? This would explain the fuel pressure issue. I don't know the specs on your pump.

I was actually thinking that the return line could be too small for this pump. I've read of other fc with this pump though in the 200 and 300 hp ranges. I'd be surprised if they all replaced their metal return line for modest hp setups. I checked the flow from both the fpr and the return line at the tank and the flow seemed great.

The fpr is an aeromotive 13129. In their description it says it handles pumps capable of 1000 hp so it should be able to handle my pump. Here's what's interesting though, aeromotive says it's a 40 to 70 psi regulator, everywhere else says it's a 30 to 70 psi regulator, and my gauge currently says it's adjusted to 23 psi static. So something isn't adding up and im betting it's the gauge. Im going to hook the gauge directly to the regulator next time im under the hood to see exactly what the pressure is at.

However even if the numbers aren't exactly accurate the pressure is still going up instead of down. I'll buy a cheap mechanical gauge just to be sure it isn't the gauge being completely messed up.

Update:

Fuel system has been sorted i think. I disconnected the SAFC, swapped primary and secondaries, and scrubbed the return line. Static psi is set to 37ish and when the car starts it drops down to 28. However it still wont start without unplugging the fuel pump and once i do get it started it still wont idle. Whats happening now is once i get it started and the pump turned back on i have to keep the rpms above 2.5k or it will die. With the maf propped all the way open this drops down to 2kish before it dies

I triple checked for vacuum leaks while i had the UIM off and everything was good so i dont think this is a vacuum thing.

Any ideas?

Still looking for help on this. I've done a few more things since last post in attempt to see if i can get it to stay alive on its own. I've adjusted the idle set screw and reset the TPS. I also went back through the vaccum system and everything seems to be in place. The car will now stay alive as long as I keep it above 2k rpm, but as soon as it drops below that it literally just shuts off.

Anyone have thoughts on this?

Ok so fuel is good. Spark I'm assuming is good.

Is it still back firing? Compression and timing should be checked again.

Also, your engine is ported. Who did the porting? What was ported? I have no experience with porting but I do know it can lead to the need for a high idle if done incorrectly.

What I can say for sure is that if your fuel system, ignition system, timing settings and compression are OK, you have zero vacuum leaks and your car can't idle below like, 1500, then you might have a build issue.

Have you ran it for any amount of time? It may need to just run. If you aren't overheating or leaking and pressures are ok then run it for some time. You might surprise yourself.

TPS would not cause your issue.

If you haven't I would be absolutely certain that all injectors are working as they should.
Re-check the timing. So many times people think they have it timed and it isn't.
Above all: CHECK COMPRESSION.

If you read enough threads on here you will see a pattern of people doing loads and loads of work, throwing money into the engine bay, just to realize that their compression just wasn't good enough. I can't imagine how many good TPS end up in a dirt pile -it hurts the soul. It's the first test that should be done to avoid the grief. If it checks out then you can sigh in relief and move on.

It doesn't backfire at all anymore while I have it above 2k rpm. It sounds good even.

I've checked timing 4 times now but I think it's time to invest in a timing light just so I can be 100% sure that's straight.

I did the street port myself using a mazdatrix intake template and a pineapple racing exhaust template. Im sure they aren't perfect but I took my time and tried my best. I felt like they came out well enough but it was my first attempt so as I said, I'm sure it wasn't the best port job ever.

I really doubted it had anything to do with tps or idle settings. Was just kinda grasping at straws. I guess I can't be 100% on the vacuum either. Everything is certainly hooked up but it could still have a leak somewhere. Problem is I can't get it to idle so I can't spray starter fluid around the hoses or manifolds.

I'll start with timing and compression though since those will be fairly easy to do.

Thanks for the suggestions.

.

Always glad to help.

Could you perhaps take a photo of your CAS(with the blind cap off) with yellow mark lined up with timing pin?
Try to take a photo straight on with zero shadows and take a close shot. I'm interested to see your settings just to cross it off the list.

Post back with a photo and compression readings.

I ordered a compression tester and timing light online. Should be here Friday it says. In the mean time here is the photos of the timing. Note that I don't have the red and yellow paint anymore. I set my tdc to the first(right) timing mark.

https://cimg6.ibsrv.net/gimg/www.rx7...73a0c5f8c3.jpg
https://cimg0.ibsrv.net/gimg/www.rx7...cf1aad14c6.jpg


Also something I forgot to mention last time. My boost gauge was showing that the car was pulling like 15 inhg of vacuum while it was running. Not sure if that's indicative of it being vacuum leak free or not. That seems to be in the ball park of other rx7s from what I've read.

Do you see how that bottom small tooth is kinda lined up with the contact?

Turn the CAS counter-clockwise so that contact is exactly half way between the one that is lined up with it now and the previous tooth.

that will get you closer to perfect.

Try that and and see if it idles lower.

Finally got to the car today. To start, the car started on its own without having to mess with the pump for the first time which was nice. Not only that but it "idled" on its own at 2.5k for about 20 seconds before dying which was also a first. Aside from that it was business as usual. Falls on its face immediately after it drops below 2k rpm.

I tried turning the CAS as suggested. The car does sound smoother now. Before it would pop constantly. Still does pop a decent amount but not nearly as much, as you can hear in the videos I linked.

I tried checking timing with a light, but at 2k rpm its just impossible to see the timing marks. It should be close enough to run at this point so I think we can rule out timing.

I also checked compression. It was hard to tell individual face readings, but they were all consistent with no sudden drops in compression from one face to another.

Front compression: 60 psi
Rear compression: 65 psi

I know those numbers are not great, but its a fresh rebuild with new apex seals and used housings. From what i read that's normal to have low compression for awhile.

Videos:

"Before timing change front"

"Before timing change rear"

"After timing change"

That's good. These videos are unavailable to me for some reason. You're timing is close enough that is should be able to drop below 2k.

Is the brake booster line hooked up on the intake? Just an idea, it's happened to me.

Another idea... have you set your throttle body? Maybe you're choking yourself out? Just brainstorming.

After it dies does the car start easily afterward? If it does that is a good sign. I'm running out of ideas.

Oops videos were set to private. Should be able to view them now.

Yeah brake booster is hooked up. I don't know what setting the throttle body is. Like the idle set screw?

Historically it hasn't started on its own ever lol. This was ther first time I turned the key and it fired up. I ran it up to operating temp for the compression check so I didn't get to try a second cold start. It does not start up without messing with the fuel pump while it's hot though. That's probably just the low compression while warm though I assume.

It's kind of a pain in the ass to set but it's very critical that the throttle body is set properly. Butterfly clearances mainly. If you consult the FSM you'll find the info.

Question: Does the car start on it's own and hold 2000rpm and THEN it dies after it warms up? If so then maybe your throttle isn't set properly and after the high idle cam rolls off you choke yourself out. Hard to say over the net lol.

That last video did sound a bit smoother. Keep it there until you get a light on it. Even if you were off by 5 degrees you should still get lower than 2000rpm. I wouldn't worry just yet. You still have a few things to look over.

Are you positive you don't have a post-AFM leak? When I first bought my TII I had a leak in the TID which showed a similar symptom. Car would stay running as long as I held the throttle.

Cool I'll definitely look into setting the throttle body tomorrow. I did the throttle body mod so do I still have the high idle cam? Today was the first day it held idle at all so its hard to say if that's the habit it's going to have.

Checked the throttle body today. The bottom two plates were within spec. Top plate was over double the spec so that got adjusted. Idk if that could be the issue though. Wouldn't that make it idle high if the plate was open more?

However what did happen was this.
https://cimg1.ibsrv.net/gimg/www.rx7...ccf61b0264.jpg
I don't know how or when the hell that happened but it must have been cracked the whole time to suddenly just snap. So maybe I have been battling a hidden vacuum leak all along?

Anyway I guess I can't really go further until I get a new UIM.

neither situation was helping your cause. you may have just solved your issues. i guess we will see.

good luck with it.

Blessing in disguise, and the manifold should be cheap. Hopefully you report back good results after replacement :)

Keep us posted!

It runs! Looks like the manifold was the main issue all along. It "idles" at about 400 rpm right now though. Timing is way off. Looks like its pretty well advanced. Which is odd because it's been set just like the fsm specified so im not sure why it's so off.

Anyone know which direction I have to turn the cas to retard timing?

Alright got the timing all sorted. Both leading and trailing are on point. Still runs like crap though.


This is it running between 750 to 1500 rpm.It sounds very ticky. Almost like it has a rod knock.

When it is around 1500 and up the vacuum is about 18 inhg but as it gets closer and closer to 750 rpm the vacuum starts to plummet below 10 inhg.

you made progress and that's great.

have you tested your BAC? also, what do you know about the port work done to it? basically, i'm curious just how much more overlap was introduced.

if you're referring to the "ticking" noise i heard in the video, it sounds suspiciously like an exhaust leak.

No bac. Previous owner deleted it.

I ported it myself. Ported with mazdatrix street port intake template and pineapple racing ep2 exhaust template. So a pretty average port job in terms of size.

I think the ticking is an exhaust leak as well actually. I had custom exhaust work done and never double checked if the guys tightened everything down well.

As of right now im thinking I may still have a vacuum leak just because of how the vacuum fluctuates at low rpm. Might be time to start spraying carb cleaner around the engine bay.