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Need some help troubleshooting (i searched, promise)
Ok guys after spending some hours this week trying to figure out what's going on the with the chump car here's what I've got.
The car free rev's in neutral up to about 5-6k fine, but will not go past 3800 under load while driving without some real coaching, also stumbles / hesitates at some lower RPM's as well. Stop before you start yelling about grounds and read on.
My car is a chumpcar, see build thread for more info. Basically 5th and 6th ports are wired open, no emissions equipment, no OMP, no accessories other than alternator / water pump.
- Car is an '86 S4 w/ N326 ECU. Pic added.
On the fuel injector side here's what I know.
- All injectors seem to be wired correctly, and the resistor packs check out (12-15ohm resistance on all 4 injectors).
- I directly wired the ECU and block grounds to the battery to try and remove any "grounding" type issues. Also cleaned and re-wired the coil and chassis grounds that are on the car
- - Didn't help.
Tonight I checked the timing with a light, the CAS was fully advanced so I thought something was wrong, when I tried to put it back to the marks the car didn't want to run @ the 5deg ATDC mark, so I found TDC and reinstalled the crank angle sensor. Idles pretty good, free rev's as before, will not drive fast
I used a stethescope to verify the all primary's and secondaries are firing above 4000 RPM, so at some point the whole thing works, just not while driving.
Fuel pressure:
Regulator / pump check out (40PSI w/ no vacuum max RPM, 34 PSI @ idle, 60 + PSI / crimped line)
- Pump is wired for max RPM all the time
The following systems all check out within spec:
- Double Throttle
- Boost Sensor
- Ambient pressure sensor
- Water Thermo sensor
- Air flow meter / IAT sensor
Here's where I'm at:
- Could have plugged injectors
- Haven't been able to check fuel pressure while driving, fuel filter could be plugged
- - It's pretty new, so I think I would have seen a drop trying to free rev the engine to red line w/ the throttle WOT... It's pegged @ 40 the whole time
- There are two switches in my car (one for the fuel pump, 20A fuse, and one for IGN (20A fuse)
- - The EGI fuse on the OEM fuse box seems to be a 30A?
- - My ignition switch runs coils, injectors, ECU, basically everything but the fuel pump and wipers
- - Should I try a 30 or 40A fuse here?
- What else ya guys got? I'm stumped here. The motor seems to be healthy (compression checks out) but it has no power... Sometimes it won't even get past 2000 - 3000 RPM.
I'm sorry for making this tough, this car has been so heavily modified that I don't think scanning the ECU for codes will help. Could we be stuck in some kind of limp mode?
Throttle position sensor: It checks out w/ an ohm meter, but I haven't built the light setup yet to learn the correct position
- - both my leading and trailing coil are firing @ the same crank angle. Could this be part of the issue? I heard this was just a TPS symptom.
Does the idle mixture resistor affect any of this? About the only thing I've been able to do on this thing is to get it to idle well.
Any opinions on what else to try would be much appreciated. I know a decent amount about cars but this is ma first rotary and it's a bit of a history lesson w/ something this old.
Thanks,
Andy
Last edited by sodamninsane; 07-14-15 at 11:23 PM.
If the car is an S5 and you have NO Omp..
LIMP MODE.
You can't take the OMP out of the ECU equation without the car going into limp mode.Either it has to be attached to the harness and put aside or you get an RTEK and run the car with that ECU.Then you can take the OMP off the harness.
If the car is an S5 and you have NO Omp..
LIMP MODE.
You can't take the OMP out of the ECU equation without the car going into limp mode.Either it has to be attached to the harness and put aside or you get an RTEK and run the car with that ECU.Then you can take the OMP off the harness.
Thanks should have been more specific, the car is an 86 model year S4 13B.
Also, not sure if the cal's can be transferred, but the car has the "standard?" N326 ECU.
If the car is an S5 and you have NO Omp..
LIMP MODE.
You can't take the OMP out of the ECU equation without the car going into limp mode.Either it has to be attached to the harness and put aside or you get an RTEK and run the car with that ECU.Then you can take the OMP off the harness.
I've hard wired the coils and injectors w/ no fuse for now.
- On order is an 80amp relay + fuses, basically going to power coils, injectors off one circuit through the relay, and then ECU off another.
I've checked all the ECU grounds, and added an additional chassis ground for pin 2C (map / boost sensor).
Car runs, still has some hesitation on the way to redline while driving, but I think that's due to the 5th and 6th ports being blocked open, and also that I haven't been able to get it very hot.
- Car isn't "street legal" hottest I've been able to get it going through the neighborhood is about 160F (75C).
No real drop outs though, just some drops in power on the way to redline.
I think I've got all the electrical gremlins sorted out. I have to weld in a window net and investigate a leak around the fuel pump access cover on the gas tank so I might pull the injectors while I'm doing all that and look them over.
07-14-15, 09:01 PM
Need some help troubleshooting (i searched, promise)
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