Random Miss Under Load (Page 1/1)
T Top 88 JUN 04, 03:22 PM
Hi all, recently I’ve been having an issue with my 2.8 V6 (88GT) where the car occasionally will miss under load in lower RPM ranges >1700RPM. This happens very randomly, and only in the lower rev ranges, the car will pop once or twice, and then pull hard. It doesn’t feel like it has a lack of power at all.

The car has a brand new cap, rotor, spark plug wires, reasonably new spark plugs which are properly gapped and look clean (no oil or deposits) when pulled. I’ve timed the car with a timing light that as far as I know is accurate. The car idles really smooth and on very rare occasions has a slight miss (makes a little pop from exhaust).

Has anyone had this issue before? At this point I’m thinking it’s either a sloppy timing chain issue, as the car has 140,000mi on it at this point in time, or a weak pickup coil, which is the only ignition part that hasn’t been replaced. I have swapped ICMs with a Fiero that doesn’t have this issue, and the problem was still there. Thanks in advance!
Patrick JUN 04, 04:50 PM

quote
Originally posted by T Top 88:

I’ve timed the car with a timing light that as far as I know is accurate.



Always worthwhile to ask the following questions...

Was the ALDL jumper in place while timing the engine?

Have you checked to ensure the outer ring of the harmonic balancer (which has the timing marks on it) hasn't slipped? Need to make sure that piston #1 is at TDC when the widest of the three timing grooves is at 0°.

[This message has been edited by Patrick (edited 06-04-2023).]

T Top 88 JUN 04, 05:37 PM

quote
Originally posted by Patrick:

Always worthwhile to ask the following questions...

Were the ALDL jumpers in place while timing the engine?

Have you checked to ensure the outer ring of the harmonic balancer (which has the timing marks on it) hasn't slipped? Need to make sure that piston #1 is at TDC when the widest of the three timing grooves is at 0°.



The ALDL had the jumpers in place, but I’m not sure on the harmonic balancer. That’s a good idea, and I’ll have to check that. Thanks!
Doug85GT JUN 04, 06:33 PM
I had a similar problem years ago. It turned out one of my wires had a small crack in the insulation. I found it by idling the car and misting water around the wires, distributor and coil. All you need is a spray bottle filled with water and a little darkness. If anything arcs when you mist it with water, that part is faulty.