JoelChicago

Car: 88na conv., 101K mi.

I've seen so many people with this problem, and now I want to definitely get to the bottom of it, since my car has it occasionally and I hate it. Adding engine grounds didn't fix it. I'm checking the CPU ground this weekend. Ran Chevron/Techron in last tank of gas. Refilled yesterday (87 oct Shell), hesitation still there, actually a little worse. Fresh fuel filter, MMO in the oil currently.

I'm noticing my hesitation is FAR more pronounced when cold. When fully warmed up, it's OK - no hesitation. Also worse in first gear. This morning (here comes the twist), I had strong hesitation at 5300 RPM AS WELL until the car was warmed up!!! So, the question is - what sensors/equipment influence the car when it's cold? I'm guessing I'll start with an O2 sensor and go from there. Need your thoughts though on what else could affect secondary injectors! Under 3500 rpm, she runs like a dream.

Also, I'm replacing plugs this weekend with NGKs (already bought 'em). WHICH ONES ARE LEADING, WHICH ARE TRAILING ON THE ENGINE? Front 2 leading?

Thanks everyone.

SureShot

All the secondary intake stuff should be full on by 4000. The plugs should fix it, if not maybe check if the 6-ports are sticking - opening late?
Bottom = leading. Top = Trailing.

MikeL

My '87 TII had the 3.8k hesitation. I never tried any of the fixes. When I installed 720cc secondary injectors and a S-AFC, the hesitation went away, completely. I guess I covered it up with fuel.

von

Open hood. The very front rotor closest to u is rotor 1. Sencond or closest to steering wheel or driver is rotor 2.

top front is T1 and bottom front is L1

Icemark

Seen that on two '88 verts with the 338 'puter. Its a cold solder joint on the plugs in the puter.

Only happens when really cold.

Plugs and plug wires won't fix it. When cold the O2 sensor is not working yet either- needs to heat up.

Thaniel

I have the same thing going on with mine. If i pull the vac line off the boost sensor it runs great. Haven't found the cure yet. Been busy/sick.

Thaniel

TRURX7

Well this is how I fixed it and I drove the car 800 miles to New York to prove it.

The Car: 87 NA

The Problem: When cold car ran perfectly. After 5-10 minutes of driving, would barely climb RPMS after 3000 under medium to heavy throttle, progressively getting worse as fuel level went down. eg. hesitations least noticeable with full tank of gas.

What worked for me: Ran a 1 Farad capacitor wired to my custom mid-power sound system. Results were instant after resetting cpu and capacitor install.

Why I beleive it worked: Capacitor stores current which is vital to engine management components, even though it was wired closer to sound system, it kept more current available for all automotive electical and electronic components.


I was able to eliminate most sensors from bieng at fault, fuel pump, fuel injector pressure regulator, injectors, cpu by direct replacement and testing.


Good luck getting rid of this horrible problem fellas.
TRU

RLBRX7

I have the exact same problem on an 86 N/A as JoelChicago. Haven't really tried to do any of the fixes, I have been studying all I can here on the forum. I was going to begin with the grounds and progress from there.

NevadaLoneWolf

What in the hell are you doing going over 3-3.5K while the car is still cold?