very strange issue....

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DiscoPotato

Member
Oct 10, 2017
5
0
Maryville, TN
Alright so Ive been dealing with a problem from my 96 d1 for the past two weeks. Its been running rough and idling rough... but its not an all the time thing. Sometimes it will run great for most of the day and run like total ass.

Its losing power and sputtering and rough idling, like a misfire

now for the fun stuff..., I used my ultra guage for all my readings and this is were things get interesting...

when this problems occurs short term trims on both banks read a constant 0.00 and all four of my 02s will read less and .1V(something like 0.045V)

now it does not do this ALL the time. sometimes right from a cold start or just cruising and sometimes it wont do it at all for a day its random.

fuel pressure is questionable... when pump primes I get about 39-40ish psi, and when running(when its not bogging down) is about 30psi(seems not quite right to me)... I have not be able to check it under load but when revving in park my pressure will drop to about 27-28 psi.

so far I have cleaned the MAF, swapped the MAF with good known one, swapped TPS, IACV, checked for Vac leaks, I have recently changed the plugs and fuel filter, checked spark, all injectors ohmed out fine.

Im really at a loss here, and have no idea whats going on... worst of all, NO CODES.....
 
4Runner

4Runner

Well-known member
May 24, 2007
663
111
Boise Idaho
Have you checked your wiring and connection for your crank sensor? That would be worth the time. How long does your fuel rail hold pressure after you turn the engine off. How much cranking are you doing to prime the system. I know this is broad but how are your electrical connections, battery, grounds ect? Mine used to do that when I had water trapped in the ECU and depending on where it splashed determined what didn’t run right. Intermittent issues are the worst. Good luck. ��
 
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DiscoPotato

Member
Oct 10, 2017
5
0
Maryville, TN
I've already checked the ecu, it was spotless, no corrosion or anything, as for the crankshaft sensor, I checked what I could and nothing seemed wrong, I figured I would have a code for it if their was a problem with it. The pump primes instantly when the key is on. And will hold pressure for quite awhile after being shutoff.
 
Agent

Agent

Well-known member
Jun 20, 2007
669
3
WV
The crank sensor won't necessarily throw a code. The one on my DII failed without warning when I stopped to pick up a pizza on the way home from work one evening.
 
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yoseffby

Member
Nov 10, 2017
11
0
Marfa
How did you isolate it to the ecu? ... and how did you fix it? I've had the same type of thing for about 6 months, I'm going to do the adaptive reset tomorrow but would be glad to know if there's a way to figure out if its the ecu or not.
 
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discostew

Well-known member
Sep 14, 2010
7,724
1,021
Northern Illinois
DiscoPotato said:
I've already checked the ecu, it was spotless, no corrosion or anything, as for the crankshaft sensor, I checked what I could and nothing seemed wrong, I figured I would have a code for it if their was a problem with it. The pump primes instantly when the key is on. And will hold pressure for quite awhile after being shutoff.
Click to expand...

When you say it's spotless with no corrosion are you saying you took the screws out of the case and laid it all out? Cause that is one of the things I would be looking at.

I think the fuel psi going lower at higher rpm could be something. Got a long enough hose on your fuel psi gauge to tape it to the windshield?

What's the exhaust smell like when it's acting up? Sulfur smell would be raw fuel in the cats. If it burns your eyes it might be lean.

Pull the vacuum line off the fuel pressure regulator and see if it's got fuel in it. And one last thing to look at is your TPS voltage when it's acting up. Kind of a long shot but worth looking at. If it drops off really bad when this happens DONT go buy a TPS sensor. Just report back.
 
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