Hey guys I looked around and found some threads that gave me insight but I want to get some more thoughts from you to sleep on.

So I have an 88 t2, stock turbo, stock engine. I just installed an rtek 1.8, 750cc RC injectors, rising rpm fuel rails and AN converted fuel lines, corksport intake, turbo-back exhaust, and a full emissions delete. Car started right up, took a little to find idle, but sounds healthy.

The trouble begins under boost. If I take off and quarter throttle the car to around 4000-4500rpm and then floor it, it snaps right into acceleration without any hesitation or sputtering. Spools right away (stock turbo) and pulls until about 7000 where it starts to sputter.

If I am driving flat or up a hill at like 3000-3500 and give it more than a quarter throttle, it will sputter and then surge, over and over. If I floor it before 4000, it will pull to about 4500, then bog way down, then surge, etc.

Now like I said I did an emissions delete, using all rising rpm block off plates and fresh paper gaskets. Could one of these be causing a boost leak? And it might be my imagination but I don't remember the boost gauge needle spiking almost vertical on the stock gauge (I don't have a boost controller or anything weird that would up the boost). Do I have a blown turbo? Stock fuel pump not cutting it with the rtek and bigger injectors?

Before I did the ecu, fuel system, and exhaust I never had a hesitation or studder issue at all. Just a leaky exhaust and fuel cut at redline. Any thoughts? In case you can't tell, this is my first seven, although I did my research before I did these mods. Thanks guys.

 

Do a smoke test for vacuum leaks. It seems you may have an issue with your secondaries kicking in, so I also recommend checking your grounds. Aaroncake's write up is the best guide imo. Proper RX-7 Grounding Procedures

 

lovely, no boost gauge and no wideband. a perfect recipe to pop a motor.

throw us a bone, without ANY numbers we have absolutely no frigging clue what your problem could be.

 

Well even with the rtek chip the ecu will still limit boost to the stock cap, so technically I shouldn't have to install a boost controller, or a wideband, unless I'm misinformed. I have a manual boost controller that I had planned on using later down the road, but I can install it and see if that will keep it from spiking. I have a nice aftermarket analog boost gauge as well that I can use to reference the actual pressure.

 

And I did a few extra grounds as well, so I don't know if grounds are the whole issue, although I did read about I jectors acting up with faulty grounds. I replaced the factory block to firewall ground with 4 gauge, grounded the exhaust with 4 gauge, and redid the battery ground.

 

That ground write up is excellent thanks for that. And I'm going to smoke test it this weekend and see if I left something undone or if a vac line is missing

 

What fuel pump?
What boost are you seeing?
What intercooler are you using?


Rtek's (or another ecu) cannot limit the boost produced. That is the wastegate's job. ECU's and manual boost "controllers" can only set a minimum that the wastegate tries to maintain.
In your case with a free-flowing exhaust, you need to port the wastegate.

The Rtek defeats the stock safety feature that prevents engine damage to to over boosting. It's better than a fuel cut defender, but it still removes a safety feature.

 

no it wont.

you also need a larger fuel pump, as the stock one is only sized for 550cc x 4 injectors, and you have more than that

 

boost controllers cannot lower boost.

the ECU also cannot limit boost, since the ECU does not physically control the turbo at all on the FC. the Rtek in fact removes boost cut so you can go into unsafe boost to the point of grenading the engine if you have no way of watching the important aspects of how your engine is running.

this isn't a modern car, most modern cars the ECU has some control over the turbo via a wastegate solenoid but the FC never came with any of that fancy stuff, or a wastegate sized appropriately for modifying the car and maintaining appropriate boost levels.

as mentioned, if you are on the stock pump that's a good place to start. the next place to start is by getting a boost gauge. after that a wideband oxygen sensor and gauge is a good investment. the best investment for you right now is to keep your foot off the floor before you do drop an engine.

 

Thanks guys for the input. I guess I was a bit misinformed about what effect the bigger exhaust and rtek would have on an otherwise stock setup. I do have an electronic AFM gauge that will work with a wideband, and I have a greddy analog boost gauge that I will install. I will be buying a new fuel pump as well next.


I guess I just figured the boost would not be effected by the exhaust and fuel system as long as I didn't go turning it up with a controller or porting or anything. This is my first turbo car that I have done completely on my own, so there is still a lot I don't know.


As for the intercooler, I still have the stock top mount installed. I do have a greddy front mount kit and blow off valve, but I am now leaning more towards a V-mount setup so I don't run into any cooling issues later down the road.


And as far as porting the wastegate goes, I had planned on sending out a spare turbo to BNR for a stage 2 or 3, so it might be more cost effective to have that done or go aftermarket with an external wastegate. I haven't looked into it but can the stock turbo's internal wastegate be ported out enough to get where I want to be? (250-300hp). I cant remember if BNR ports the hot side at all when they upgrade, I know they do a ported cold side with a bigger impeller.

 

don't worry about it, i'm an ******* but only so that people listen in order to save them big headaches and empty wallets.

a simple way to think about it is, anything that increases airflow through the system will affect the wastegate and its ability to manage boost properly. the stock wastegate cannot handle almost any decent single mod, let alone multiples without boost creep showing up. too much creep and not enough supporting mods/tuning = boom.

another thing to keep in mind is, surging and misfiring in boost is a big red flag that the engine is telling you it isn't happy and that something bad is about to happen.

 

Thanks RE. I will be giving BNR a call and seeing if they widen the wastegate when they upgrade stock turbos. Thanks again guys probably saving me tanking the motor without even knowing what the problem was.

 

Idk alot about turbos, but isn't the stock wastegate on the exhaust manifold? At least the flapper is IIRC

 

nope. that flapper is the twin scroll thing. it closes half the turbo at low speed, to try and get the turbo to be more responsive.

 

He does the wastegate mod on all his upgrades.

That 's the S4 twin-scroll system, not the wastegate. It does use similar hardware and is located in the same area.

 

The stock ECU has no way to control the boost. The wastegate nipple is plumbed directly into a boost source. When the exhaust or intake is modified to allow better flow, boost will creep very easily.

 

Yes thanks again guys.

Well I have narrowed my issue down to either operator error during the install or my fuel pump isnt cutting it.

Went to start it today to baby it back up to the shop and it took like five full minutes of dry cranking before it even caught a little bit. Had to keep my foot on the pedal slightly to get it to warm up, wouldn't hold idle. Sounds fine, but wouldnt idle until it was fully warm, which is a first. Pulled out of the driveway and 1/4 throttled it to third year, but when I came to the first hill on my street, engine loaded up, barely made it to 2psi before backfiring and spitting until I let off the gas. Stalled every time I stopped on the way back home like a mile away.

Opened the hood and everything looks fine, not leaking gas, no smoke, no excessive heat, no intercooler pipes disconnected. Thiink the stock pump isnt cutting it and has just about had it. I'm going to try a walbro 340 this weekend. What a headache.

 

Has power and compression and drives, just wants nothing to do with boost. Something is seriously fucked up

 

sounds like a boost/vacuum leak, double check your intercooler hoses and any large hoses connected to the intake manifold.

 

Yeah just checked and everything looks good from what I can see without taking anything apart. Both intercooler hoses are still on and tight, and there are no loose vacuum hoses that I can see.

It could very well be one of the block off plates I installed. They are all rising rpm anodized aluminum, and I made new gaskets with gray gasket paper, which might be where I went wrong. I will either try rtv or order factory gaskets for each deleted part. Before this I will try a smoke test to see if I can pinpoint the issue.

Also ordered an aeromotive 340lph fuel pump and I grabbed a wideband from where I work to cover my bases once I figure out what is leaking.

The other thing is I followed the emissions delete on rotary resurrection and used JB stik to plug up the small hose port on the pipe between the turbo and stock top mount and the bac port on the intercooler. I wonder if these could be leaking? Upper intake has new gaskets and the air charge pipe has a new o-ring and I never removed the throttle body from the uim.

 

you have a leak, take it to a shop, ask for a intake smoke test. or go buy the damn machine, but your eyes are not the proper tool for the job.

 

Yeah that's about where I'm at by this point. Thanks for the help guys.