clamaro

Hi everyone. I have been struggling with this issue for about a week now. When I first drive in the morning, the car runs perfectly. As soon as it warms up, however, the idle surges at a stop and the acceleration is jerky and feels much less powerful. This issue lasts the whole day. Even after the car sits for four hours while I'm at work the issue starts the second I fire it back up. I have fixed a few minor vacuum leaks and replaced the fuel filter. This issue never happened on my old distributor. I put a new MSD billet distributor in it last week and it ran like a top for about five days until this issue began. Any ideas would be greatly appreciated.

clamaro

Just a quick update and some more details I forgot. I have cleaned the MAF and it did not change anything. Today after class I started it up and it ran awful. It bucked and barely accelerated and was backfiring. After a few minutes driving it smoothed out and the surging was barely noticeable. This was after sitting for about three hours.

hrcslam

Did you do the ICM spacer mod? Of not, give that a go and see if it helps. If it does, look into a new ICM.....

Vicious95Z28

iTrader: (1)

Does the car still have EGR?

clamaro

I have not done the spacer mod yet. That is on my list for Saturday when I have a chance to work on it during the day. And yes it still has EGR. I pushed the diaphragm while the engine was running and it almost stalled so I took that as the EGR working.

myltwon

iTrader: (1)

2 most common types of problems that arise when a car reaches operating temps are either faulty ignition components (failing electronics will show more issues when faced with higher heat) and sensors that only read during closed loop (i.e. o2 sensors).

Since the issue came after the msd unit was installed, I would replace it with an oem unit.

clamaro

So are O2's the most likely culprit or should I just replace the opti?

hrcslam

The spacer mod is much cheaper (free) and easier. It'll help you elliminate or isolate the ICM as the issue.

Did you replace all the spark plug cables?

clamaro

No I have not done plugs and wires. I assumed they would cause problems when cold as well.

hrcslam

Not necessarily. Heat can effect continuity. I had my coil to distributor wire corrode and it caused some weird issues when hot.

clamaro

If the ICM spacer doesn't fix it I'll do new plugs/wires. Should I go with AC Delco for both?

clamaro

Here's a video I just took of the car at idle. The coolant was just under 160 according to the gauge and the car had been sitting for about three hours. This is right after startup. I never once touched the throttle.

hrcslam

Can you Data log? I'm leaning towards the opti now. Sounds like it's missing then catching, then missing, then catching.......

Did you get just the cap and rotor or the whole opti from MSD?

I'd still try the ICM spacer mod though. They get hot all on their own, add in head heat and it can get messed up. And they are super easy to do.

clamaro

I don't have a scanner so I can't data log. I got the whole opti from MSD.

BTC

Do you still have catalytic converters on your car?

ACE1252

I'd try a quality set of plugs and wires first if it feels like a miss when driving it.

Before doing that, make sure all the wires are seated tight on the plugs, opti, and coil just to rule out a loose wire. Double check any wiring harness you touched during the install as well.

Just because I don't know...question to the forum.....Do the MSD units still have trouble with the screws backing out of the rotor?

Also might not hurt to make sure that the screw that adjusts the timing on the MSD unit is still tight(and set at 0...at least I think it's 0). I'm assuming they still have that adjustment.

clamaro

Yes I still have cats. When it quits raining I'll go check on the plug wires. My distributor does have the timing screw.