RideBikes

Hey guys,

I need help trying to diagnose the problem and why it won’t start, first a little history:

So I started my swap back in October 2014, me and my friend figured it would be relatively straight forward and we could have it up and running within a month..well as it turns out swapping a S4 T2 motor into an S5 NA chassis is extremely difficult, for me anyways.

Some history on the car itself is it is a 1989 S5 NA, it was originally auto but the previous owner did a manual transmission swap. I have been using the car as a weekend car and part time drift car, I have modded steering angle and a gutted rear end along with the S4 LSD diff, but other than that the car was mostly stock.

The engine is an S4 T2 that was rebuilt about 20,000KM’s ago, everything was more or less stock with the motor itself other than a street port, and apparently upgraded fuel injectors (that look like the stock 750cc ones to me..).

I have switched all electrical and other surrounding parts on the motor to S5 (LIM, UIM, throttle body, wiring harness, ECU, turbo) so that all will plug in and be compatible with my S5 chassis. I have not fully deleted the OMP yet, but I do have the S5 OMP plugged in and nestled out of the way for test starts. I used the stock injectors that came with the engine and just soldered on the S4 clips to the S5 wiring harness; I know, S4 are low impedance, but I also know that later S4 models used high impedance injectors which I am sure I have.

My problem is that when I try to start the car it will turn over 1 out of 4 attempts and when it does start it idles for a short period of 5 seconds and stalls out like it is starved of fuel, though there was one day that it idled for a solid 5 minutes and it never did that again.

I have searched the forums relentlessly for answers and have not been able to find anything that I have not already done, so I have turned to creating my own thread in hopes someone may bestow some mind blowing knowledge on me.

I have checked all wiring and circuits with my friend who happens to be a journeyman mechanic, so electrical, for the most part is out; there is always room for error so I would be willing to revisit the electrical testing.

I have pressure tested my cooling system and it holds pressure just fine, though I still need to check compression.

Please let me know if you guys have any ideas. With that said, please ask for any information I have left out, there has been lots done in the past few months and I am sure I left out some information.

Any useful input is greatly appreciated.

RideBikes

Still needing help on this, anyone have any input at all?

invinciblejets

Are you sure the injectors aren't low imp?

DR_Knight

iTrader: (23)

What ecu? N370 or n374?

satch

iTrader: (1)

Is the turbo motor a USDM or JDM?

RideBikes

Yes, I'm 100% sure I have high impedence injectors. The motor is a USDM motor, I have to check what ecu I have though.
I did read somewhere that jdm ecu's don't agree with USDM motors and results in only one fuel rail working.
Is this true and if so is it due to the wiring harness or the engine components themselves?

I will check tomorrow what ecu I have and let you guys know.

RideBikes

So I took a look and found out that I have a jdm ecu (N374).
For test purposes would I be able to hook up the usdm NA s5 ecu to start it?
From my understanding you should be able to run the engine at idle only without doing any harm, can anyone confirm this for me?

DR_Knight

iTrader: (23)

I had a buddy who ran a s5 t2 motor with Na ecu but I don't remember if he had to do any repinning. Should be easy to search for the answer by examining process of modifying Na harness to work on t2.

Hopefully this is an easy fix

DR_Knight

iTrader: (23)

Will it run if you keep the gas up? Just saying possibility for bad coolant temperature sensor changing fuel trims. This is only second idea. First deal with the ecu. Triple check serial numbers on injectors to verify high impedance.

misterstyx69

iTrader: (142)

Ya,don't expect boost conditions on an N/A Ecu though.

RideBikes

Dr Knight, yes I have tried opening the throttle up while starting and it still does the same thing, though sometimes easier to start, likely due to additional air flow.

Well, when I get a chance this week I will give the NA ECU a try and see what happens..I'm hoping for a miracle, but expecting nothing much lol

Thanks for the input so far guys, I really appreciate the help.

Templeton

iTrader: (10)

definitely check serial numbers on the fuel injectors so you know exactly what you have.
If you've never seen these injectors actually run a car they could be bad.
you could also have a very large vacuum leak. double check. triple check.
One more possibility is any chance you reversed your fuel lines?
i've had all of these things cause similar symptoms.

RideBikes

Hey guys, finally had a chance to update my progress. I have confirmed that I have high impedance injectors by measuring the resistance between the terminals on the injector itself, resistance was about 12.5 ohms. I tried plugging in an na s5 ecu and got the same results when I try to start, seemed to be a little closer to staying running though.
I also tried reversing my fuel lines, they were definitely routed correctly as there was no luck with them reversed, not even a sputter.

As for vacuum leaks, I looked and all looks well. However, there are two open passages on the throttle body for coolant, but I don't think that would effect anything.

The next thing I want to try is test for fuel flow and pressure after. How do I go about doing that? I was thinking I would pull the fuel rail off with injectors still in and jump my fuel circuit like I was priming the system, not sure where I would jump the circuit though.

Let me know your thoughts and let me know if you have any suggestions or feedback of any sort.

satch

iTrader: (1)

You jumper the fuel check connector and w/key to on the fuel pump turns on.

You can borrow a fuel pressure tester from an auto supply store and test the pressure in line.

And your primary injectors can be clogged.

DR_Knight

iTrader: (23)

Possibility of bad afm.

Strange it ran one day idling and never again though. Power to fuel pump first controlled by computer while starting then maf takes over. Possibility it isn't sending signal. Check via fsm.

Tuned the tps?

RideBikes

Satch, I have looked for it but cannot find where the fuel check connector is on my car. I looked at pictures I found online and they do not match what I have..could you point me in the right direction?

DR Knight, you could be on to something; I still have my na s5 afm, would that work just for start? I know that one is good as the old motor ran fine. Could you clarify what you mean by checking fsm to please?

I have not tuned the tps, I thought you had to be able to have the vehicle started to do that? Could you provide a link to tuning the tps?

Again, thanks for all the input guys, eventually I will get this car running.

DR_Knight

iTrader: (23)

https://docs.google.com/folderview?i...e_web&hl=en_US

http://foxed.ca/rx7manual/manuals/te...CAL%20DATA.pdf
Refer to td6 in this. I think both have the same information. Start checking resistance of sensors. Have had a bad water sensor before a few times. My car would start but it would not want to idle at all and I had to keep on the gas as the fuel trimming was off.

Never had to deal with air intake sensors going bad. Possibility? S5 Na maf should work, the resistance it gives is a little different than t2 due to weaker spring. Check for voltage of fuel pump to make sure pump stays on.

Check timing.
Check for unseen vacuum leaks. Inspect turbo inlet duct for cracks where it mounts to turbo. This sometimes slips by inspection. Potential for leaking bov, intercooler

Let us know what happens.

DR_Knight

iTrader: (23)

If you can show pics of intake manifolds for vacuum routing to see if we notice anything.

satch

iTrader: (1)

It's part of the emission harness. Find the boost sensor as it is fed by the emission harness. The check connector will be found between the boost sensor and the engine along the emission harness.

RideBikes

Ok, I have some time to test some things later today. When I get a chance this evening I'll get a few pictures of the intake manifolds and have those posted later this week, I will also test my TPS and AFM along with the water temp sensor and turbo inlet duct.

As a warning, my current setup is just for start and may look atrocious, but I am fairly convinced it should be working fine.

satch

iTrader: (1)

In case you did not know, but if you have the intake snorkel disconnected from the AFM or throttle body the car will not run.

RideBikes

Hey guys, so I tested everything I said I was going to and got mixed results. When I tested my AFM the resistance readings were perfectly within the parameters found in the manual I have, so that I know is good.

I managed to find the fuel test connector finally, it was painted black with carbon and tucked under my AFM so it was hard to find. When I tested my fuel system I pulled the fuel rails off with injectors still in and held them over a rag, testing them one at a time for fuel flow/leakage. The primary rail seemed to have appropriate pressure, no fuel came out of the injectors themselves but there was fuel present in the rail itself. The secondary rail however did not seem to have to have as much fuel pressure but it did seem to have fuel in the rail, as when I was putting the system back together one of the injectors popped out a bit and leaked fuel.

So I know I have fuel going to the rails, don’t know whether or not it is the correct pressure though, how do I go about testing if the fuel injectors are actually firing/spraying fuel as they should? Would I just perform the above test but turn the motor over while doing so? I’m fairly certain that my fuel pump should be all good as it is a relatively new-ish Walboro.

If the intake snorkel you are talking about is all the piping in behind the AFM leading to the turbo then yes, it is all there and to my knowledge connected correctly. In double checking this part of the motor I found what may have been a vacuum leak, so I fixed that to make sure it doesn’t cause me any problems in the future.

I will have to figure out how to link photos, but I do have a few, though not with the motor all together.

RideBikes

I managed to perform a little more testing the other day and found that my TPS is not quite on par with what it should be. The narrow range tested 1.3K Ohms and the full range tested 1.6K Ohms, the narrow range is just a bit out I think but the full range is way off..is there a way to adjust this or is the TPS toast? Could this possibly be the cause of the no start issue I have been having?

Another thing I was wondering about is the knock sensor, I believe it is in different locations on the S4 Vs the S5 motor, that shouldn't be an issue but should it plug in the same and be of no issue?

satch

iTrader: (1)

A TPS should not affect starting.

lastphaseofthis

iTrader: (8)

the tps is also reading high because your motor is COLD.... the AFM plays a large roll in starting/running. try keeping it open with a screwdrive stuffed in the front, see if it runs longer/different.