I have a 95 Impala SS with 57000 miles. It had a very slight miss in it just enough to be noticiable. Took it to a shop and he put the computer on it and said my PCM for less tune was right on and everything looked good. He thought maybe an Opti. It got worse after a few days. I ordered new NGK Tr-55's and MSD wires. Gapped the plugs at 0.50 and installed them and the wires. No more miss but the car just does not seem to have the power it had. Stock motor with a Comp cam 218/224 1.6RR's and new springs. If the Opti was not sending enough spark could that be the problem or the coil. Or maybe plug gap is wrong. It will hardley turn my new Kuhmos over. What do you guys think. The Impala forum is down for maintanence so I really need some help here.

Thanks
Jeff

 

Check you knock counts. Could also be a clogged cat.

 

I have LT4 Knock sensors and when the shop put it on the computer he said it was not reading any knock. I seem to have god exhaust out each side.

 

Anybody have any ideas?

 

Assuming you don't have crossed wires from the last plug install.

All the Standard Auto Parts sensor classes warn to look out for cotton air filters like the S&B contaminating the MAF. The symptom is exactly as you mention.

First try cleaning the MAF and BTW brake cleaner leaves a residue and is NOT recommended. If the MAF is causing the issue, it is easy to test with a multimeter.

 

All the wires are correct. Checked them again last week. MAF is clean just checked it the other day when I cleaned my filter. How would I test my MAF with a multi meter?

Thanks
hoppy

 

How did a shop hook a computer up to your car and know that the PCM4Less tune was right on? Why did you have a shop install the LT4 KM? It is a very simple install.

If the miss is gone, then you can rule out the opti, coil, or plug gap. How do the plugs look now that you've put a few miles on them? Do you have scanning software?

 

I guess he hooked up some kind of scan tool to the computer. I did not see the screen. We took it for a ride and he told me everything was good. Said the O2 counts were good said the tune was right on and that the miss I had felt like the Opti or plugs and wires. I installed the LT4 knock sensors. It has no miss what so ever it just feels like it is pulling a lead weight behind the car. It runs fine as far as just driving back and forth to work. But when you get in to it you can tell something is not right. Just no seat of the pants power like it had before.

Thanks

 

I don't know. It sounds like your timing some how got retarded. I don't know how the car would slow down after a plug and wire install and not have any signs of missing. Did you check and see how the plugs look?

 

No I have not had time. Plan on looking this weekend.