Hi again... My 1988 Pathfinder (VG30i, V6) is deciding not to start.. The ECU diagnostics check good (code 55) but there is a failure to detect the accelerator when depressed in Mode IV.. (Idle switch detection ?)

I did get it started a couple weks ago.. It would hesitate (cough and sputter) when the accelerator was depressed quickly, but would come up to high speed if depressed slowly, and I was able to drive it around town without a problem.. Once home again and parked, it wouldn't restart again.. sigh

Is the Idle switch failure enought to cause this, or should I be looking somewhere else? (ie, timing belt slip, etc).. I have check the obvious (fuel and spark)..

Happy Motoring,
Dr Obscure..

The idle switch is used for diagnostics only, IIRC.
Check manifold vacuum to the fuel pressure regulator at the back of the TB.
Check fuel pressure.

Don't have a pressure gauge, but I pulled the hose after the fuel filter, and it squirts gas about 24" into the air, so thought it was good...

I will check the vacuum.. what kind of value should I be looking for?

quote:

Originally posted by Dr. Obscure:
I will check the vacuum.. what kind of value should I be looking for?

Really sucky...

I don't recall. I diagnosed mine with a hand vacuum pump. When I increased vacuum, the idle smoothed out.
My FPR vacuum line was cannected near the top of the TB. I had to move it to a manifold port to fix the problem. I was never able to find a vac diagram for mine, so who knows what is right? I just know what fixed mine.

Of course, it still remains that I can't get it to start, so checking vacuum is moot until then

It cranks right?

Plug 6?
Cap, rotor, plug wires, coil; tried a little starting fluid and all that?

I have a '93 Ford that got weird about starting after trouble idling, and accelerating that was finally fixed by repairing a ch1tty ground connection coming off the master relay for the electrical system. I'm not sure where to look on an '88 Pathfinder but in my case it was a secondary ground wire attached directly into the battery ground cable connection that was shot.

Timing belt? After re-reading your first post and your email, I highly suspect the belt.

So... I didn't hear any clanging or banging in the engine during these problems, or the last ime it actually ran..

What are the odds that I have not damaged the engine (valves, etc) assuming the slipped timing belt.. ?? Are there any indications that I can use to verify that things are otherwise Ok? I don't want to go through the trouble to replace the belt only to find out the engine is trashed..

Just an update....
Went out today (another day without rain in the NorthWest ) and pulled the distributor cap, set the crank to TDC and verified (somewhat) that the engine is still at least close to being in time..

I am embarassed to say that I found the rotor and cap to be highly corroded, and the spark plug (#1)to be black and coatd with carbon dust... As an old school klutz, I would/should have checked that first thing.. but all the sensor crap sent me looking for a problem that probaqbly doesn't exist.. sigh..

So, I am performing a minor tuneup (plugs, rotor, cap -- wires ($60!) are soft and look pretty good yet) tomorrow and will see if that makes her run ...everything else seems to be checking out Ok otherwise...

Well, I pulled the plugs and all but one were covered with carbon soot -- installed new plugs and distributor cap & rotor..

She fired right up, even without the air cleaner and vacuum hoses attached.. now runs fine...starts on the first click every time..

I am amazed that it ran as well as it did before it decided not to run anymore.. Next time we know to check the obvious before becoming overwhelmed with the technology ...

Thx for all the help everyone!