Occational miss is now constant miss

[Teqnyck]

So I needed to change the valve cover gasket on my wifes '91 'stiva EFI and I decided to do a tune up at the same time because it had a light miss below about 2500rpm. So I just got done with all that, new plugs/wire/cap/rotor, and good stuff with brass contacts and NGK Vpower plugs. Now it's missing like crazy, sits there and sputters like a two stroke, but still only below about 2500rpm. Once I get past that, it seems to pull harder than it did before the tune up.

I did all the usuals like pushing harder on all the connections and unplugging, replugging. Checked the connection to the VAF just to make sure I hadn't bumped it out or something. I finished right as night fell and no garage, so this will have to wait until the morning, it just seems really odd do me.

The plugs I pulled out were old and worn, but had good color. The cap and rotor both had quite a bit of corrosion on them so I figured changing them would do the trick.

Any ideas you may have would be great!

[Pu241]

Wondering about the injectors.
Have you notced a change in the MPG, power loss, or just an annoying miss?

[bravekozak]

Silly question. But did you put the spark plug wires back in the proper order?
Also, check the engine ground cables.

[Teqnyck]

I don't think injectors because now that it's missing, there's a hint of gas in the air. Grounding strap it could be, I'll check that out. It doesn't explain why the miss goes away at higher RPMs though :/

[Pu241]

I don't think injectors because now that it's missing, there's a hint of gas in the air. Grounding strap it could be, I'll check that out. It doesn't explain why the miss goes away at higher RPMs though :/

Good point about gas smell.
Have you tried to isolate which cylinder(s) are causing the miss by pulling the spark plug wire loose from the spark-plugs one at a time.
When you remove the wire from the offending cylinder it will reduce your idle speed less than the other good cylinders.
If all the cylinders are similar then its likely an ignition problem.

Where are you located, maybe some can drop by and help you look it over?

[bhazard]

Clean the cap.

[Pu241]

Clean the cap.

Its new!
Read first post.

[FestYboy]

I don't think injectors because now that it's missing, there's a hint of gas in the air. Grounding strap it could be, I'll check that out. It doesn't explain why the miss goes away at higher RPMs though :/

it can still be an injector issue. when thinking of injector issues, you have 3 options: dead, stuck closed, or STUCK OPEN. if and injector is stuck open, you'll have a rich miss untill high enough RPMs are reached and that's also why you'll smell gas.

take a long screw driver to each injector and see which isn't firing, then take the handle and give that injector a good rap and see if it unsticks itself.

[beertap]

1. Check firing order (since your problem got worse after tune-up)
2. Isolate cylinder that is missing.
3. It is possible that a worn valve guide could be the problem especially at low idle.
4. Don't overlook a leaking EGR valve via exhaust entering intake.
Good luck.

[91_festy_Gl]

Could be the v plugs themselves. I know my old GL didnt like anything other then standard NGK's. Try putting the old plugs back in and see if that does anything. This might have been a old problem and now that you have new plugs, it intensified the problem.

[WmWatt]

Voltage regulator? Higher rpms = higher voltage? Try a volt meter across the battery terminals to see what the charging voltage is at different rpms? Also measure voltage out of ignition coil? Also check the gap on the spark plugs, compare to old plugs. Wider gap needs higher voltage?

[BCSpokerider]

Make sure that you didn`t leave an old plug washer stuck to the cyl head when putting in new plugs. Easy to overlook.........

[Aspire]

I actually have the same exact problem & the same actions leading up to my 97 Aspire starting to misfire. It's intermittent & it was doing it slightly before the tune-up. Now it happens about 50% of the driving time....sometimes it drives fine & revs nice & clean through all the gears & then 10 minutes later it will act up, usually at lower rpms.

At Advance Auto they pulled a P1345 code, which from reading online, seems to point to a crank sensor. I'm just going to grab one out of the JY this week & see if it works. And also try cleaning the ground cables; I think the Aspire has 2 body grounds on the engine & tranny.

[FestYboy]

festy's don't have a crank angle sensor... the 97 aspire was the only one to have one.

[Aspire]

festy's don't have a crank angle sensor... the 97 aspire was the only one to have one.

Great, I love have a "one-year wonder" car.