jpobrien

I had my 92 LT1 on a road coarse this weekend, and, on the second day, it began to inconsistantly loose power somewhere between 4000 and 5000 rpm. I thought it may have been a fuel pick-up issue due to relatively low fuel level at first, but the problem continued with full tank. I am getting an H43 ECM fault code - which is ESC circuit fault. I haven't had a chance to investigate further yet. The opti is original.

Any ideas?

bogus

ESC - Electronic Spark Control - re: Knock Sensor.

With the loss of performance, the sensor could be retarding timing... also, check the coil and coil wire. you might be having a spark problem brewing.

Sidney004

How many miles on the car(opti?) Was the problem only apparent at the race track after hard running or is it missing above 4000 all the time?

jpobrien

I'll do some testing on the street today to see if I can replicate the issue. It seemed to only do it after the engine was hot (2 or 3 laps at Putnam Park).

The car has about 84k miles on it, and I've never noticed this problem before. I've tried two previous track weekends, but did not get much time on the track for this type of thing to show up due to other problems. By the way, thank you to those who suggested I have my PS pump rebuilt by Turn One (previous thread). It functioned perfectly for the weekend.

jpobrien

Would a coil problem usually trip a fault code?

bogus

no... the coil is dumb, it won't set off a code. Check the coil wire, too. They are prone to chaffe against the waterpump, grounding out.

The opti codes are 16 and 36. low and high res signal faults. They are pretty much exclusive (short of an ECM or wiring failure) to the opti.

jpobrien

I finally got the car out to try to repeat the problem off the track. I was able to duplicate it.

It feels like it may be a fuel delivery problem. The engine only cuts out at the 4-5k rpm range at relatively hard acceleration. If the rpms gradually come up, it doesn't cut out. Fuel filter? It is a few years old, but probably less than 5000 miles. What should the fuel pressure be at idle? Would that help diagnose a problem that only occurs at hard acceleration? Also, I got no service light after the engine was warm. Engine oil temp for my test was about 235. I don't notice any obvious problems with the coil wire.

I've also noticed another problem - a ticking noise at relatively low rpm. Under the hood, it sounds like it is coming from the valves, and to me, it sounds like it is occuring on both sides, like they aren't being oiled properly. Oil pressure and level is fine. This one has me baffled, as I didn't hear it at the track at all. As far as oil goes, I'm using Mobil 1 5W-30 as recommended, but I've thought about going to something a little thicker as I am almost only using the car on the track now.

I'd appreaciate any advise you guys have on these two problems.

jpobrien

I just moved the car back into the garage - and no ticking noise.

lticforce92

You should hear the ticking noise on both sides of the engine valve covers. This sound is your fuel injectors doing thier job. How many miles do you have on the engine? If high milage (75K plus) and never had the opti replaced could be showing signs under hard accelaration (suggestion only). You may want to recheck your spark plug(s) and wires. I have a 92 vert and was experiencing partial performance under hard throttling (above 4K rpms). Took my vert to the dealership for a diagnostic and discovered that there was one bad spark plug wire. Wire replaced and I can stomp on the throttle and not one hicup beyond 4K rpm consistantly.

jpobrien

Thanks for the advise - plugs and wires did the trick for the cutout. Still have a noise that might be a knock at 2000-3000 rpm in light accelleration.

Also, the plugs that came out had at least 0.080" gap - book and sticker under the hood says 0.050". Anyone have any idea why someone would have done that?

ScaryFast

Typical rule of thumb - cutting out at hi RPM means bad wires.

The ticking could be an exhaust leak. Listen around your headers when they heat up and expand. Steel headers expand more than aluminum heads, sometimes they "pull away", especially with aftermarket headers. I've never heard injectors tick on an LT1 with the motor running, but that doesn't mean it's not possible.