-
My car is constantly running rich and will intermittently hesitate when coming onto boost, at which point I can smell petrol.
I made this thread mainly for the intermittent hesitation problem but I thought I would include the running rich problem as it could be related. I know there are many threads on running rich issues already.
It's an 85 NA2T, upgraded turbo to a T3/T4. No intercooler, no BOV. Stock fuel system. Problem seems to occur when warmed, but havent really noticed a solid pattern.
I've done the following so far;
Fixed all boost leaks
Unplugged CHTS when warm, no difference. (it's only 5 months old anyway)
Unplugged o2 sensor
No idle air controls
No cat
Injectors cleaned and tested. All new rubber hoses on the rails
Swapped ECU
Swapped TPS
Swapped FPR
New plugs BCP6RE-11 @ 0.040 gap
New fuel filter 4 months ago
Leads are 3 months old but I have extras I'm mixing and matching just in case the new leads are fucked.
Timing belt triple checked (that the teeth are correct)
Timing was at around 20degrees
Was going to swap dizzy and MAF next -
Sometimes, if the MAF isn't reading correctly, the MAF can cause the car to run rich. Though, I am not sure if it can just make the car run rich or if it is also accompanied by not being able to rev over 2-3K RPMs.
Maybe you have a leaky injector? -
I had the injectors tested like 4 months ago, but I was considering that to be a problem and was going to take them to another place to get them re-tested.
I don't have a spare MAF so I'm going to have to buy one
Car is now missing throughout the whole rev range, both when hot and cold.
Today:
Swapped back the FPR
Swapped ignition coil
Swapped dizzy w/ CAS
Compression tested - 160 - 170 across all cylinders
Swapped plugs back to old ones (old ones being 6 months old)
Swapped ignition leads back to old ones (old ones are only 4 months old) -
re-gap your new plugs to 0.035
unplug your O2 sensor
re-time your ignition
replace fuel pump with a highflow (even though the smell of fuel indicates that fuel is there, you upgraded your components so it should be done). -
Plugs regapped to .030. Will regap when I get new leads
Ignition retarded back to 15degrees from 20
Walbro GS431 fuel pump installed
Swapped back rotor cap to original
Car was running good for about 2 - 3 days. The spark plugs cleaned themselves up and the missfires had gone
Today car started acting up again. Would get hesitations at random boost levels in random gears. It would run fine again for a few pulls then go back to being shit. This cycle happened a few times in the space of 10 minutes of me driving it.
New NGK leads on the way.
Reconditioned MAF on the way -
your cas might be falling in and out of signal. i would test against another distributor from a 300zx (not a pathfinder or maxima). -
Dizzy/cas assembly already swapped as the entire unit. Made no difference.Careless;314978 wrote: your cas might be falling in and out of signal. i would test against another distributor from a 300zx (not a pathfinder or maxima).
Perhaps I should check the dizzy/cas wiring. Will need to pull up a wiring diagram, trace the wires and make sure the grounds are fine.
It kind of seems like this problem is happening when the engine is at operating temperature; intermittently at operating temp. I'll keep testing to confirm. -
The hunting issues and the 'feeling of hitting the rev limiter' are gone since the upgrades.
The hesitation still continues intermittently.
I think I've narrowed it down to ECU wiring.
I had the problem occur whilst driving, I pull over and swap ECU and the problem goes away instantly.
I've checked all the wiring near the ECU, I've rewrapped some grounds, fixed some damp spots on the floor, coated the tips of the ECU pins with some lanolin spray as preventative measures.
2 days later problem comes back, I swap ECU back to original and nothing, still hesitates. I pull the wires away from the car body (checking for poor grounds) and press the ECU plugs in hard (they sit in snugly anyway), no changes still.
Sit the ECU back on the floor of the car, wait for a bit and the problem clears up.
I have a spare wiring harness which I will inspect and possibly run around the side of the car into the ECU as a test… -
Have you checked for boost leaks?
Do you have an aftermarket temp gauge? Overheating slightly can make the engine do wierd things.
What's your fuel pressure at?
1986 300ZX Turbo…sold
1990 Skyline GT-R…new money pit
2014 Juke Nismo RS 6-speed…daily -
Yeah checked many times for boost leaks.NissanEgg;316440 wrote: Have you checked for boost leaks?
Do you have an aftermarket temp gauge? Overheating slightly can make the engine do wierd things.
What's your fuel pressure at?
Aftermarket temp gauge that sits in sump. Never shows more than 170 - 180fahrenheit.
This hesitation can even occur when the engine isnt fully warm
36psi at idle. accelerator depressed was around 40 - 44psi. IIRC . I'd have to recheck. -
I had a similar problem with hesitation under boost and it turned out to be the ecu. If you have a spare ecu swap it out and see if that does it.1985 300ZX N/A => Turbo VG33ET -
I alternate between an 86T manual and 86T auto ECU. Problems occur with both ECU.Flacster;316526 wrote: I had a similar problem with hesitation under boost and it turned out to be the ecu. If you have a spare ecu swap it out and see if that does it.
Maybe both are faulty =_= -
then your wiring has a fault somewhere. -
PTU upgraded to PRW-2.
It's been about 5 days now, the longest the car has run without the hesitation problem. -
Problem is back. It gradually returned.
Hesitation is really bad in 1st, second not as bad, 3rd is better and so on. As SOON as vacuum is @ 0 (going into boost) is when the problem occurs.
Working on a new wiring harness; some new connectors coming in the mail.
In the mean time trying a new ECU and replacing all the injectors.
Copyright © 2006–. All rights reserved. Privacy Policy