88 2.8 Corsica rough idle hesitation pinging

[88corsica5spd28]

60k miles, 5 speed. It runs better cold then as it warms up it develops the symptoms.

EDIT: it runs a lot better when it's cold out.

[Rettax3]

Start with the basics: Do a tune-up, plugs, wires, PCV valve. Consider a good-grade injector cleaner, like BG-44K. Check fuel pressure cold and hot, pull the vacuum line off of the FPR and look to see if it is leaking internally (rare on a 2.8, BTW). Consider a new O2 sensor -that operates once it has been heated enough by the exhaust gases, and if bad will cause problems like you are mentioning. Do an Ohm check on the ECT cold and at temp to see if it is functioning, likewise for the IAT. Consider blocking-off the EGR port in the intake to be sure it isn't leaking exhaust into the intake stream when it isn't supposed to (and just because EGRs suck ) -I find that a penny stuck into the gasket between the EGR and the intake manifold works great, and costs -yep, a penny . Also check spark at all six plugs when having symptoms to see if you are having a problem with a coil once it gets hot (NOT an uncommon problem with a 2.. From there, Ohm-check the injectors, then start checking wires for corrosion at the various sensors and at the ECM.

There are various threads all over this site giving detailed info on each of these procedures, but if you have specific questions about any of them, feel free to ask, I'm sure someone will answer promptly, just as I'm sure someone will criticize you for asking.

Any pics of the car? If it is a hatch-back, I will be extremely jealous of you...

[88corsica5spd28]

I did plug wires, EGR, checked the FPR, and ran a couple bottles of Techron through it, no change.
It still has the MAF so which terminals do i ohm?

Also re: coil, do i just stick a spark tester on one wire on each coil and watch for intermittent spark?

No pics yet, but it's not a hatch unfortunately. It's the ugliest car on the forum, i'd bet.


Also: thanks a lot!

[88corsica5spd28]

Pics as per request:




Told you it's ugly... and filthy right now.

[Rettax3]

Wow, that is a really clean interior, especially for being as old as it is. I like the two-tone too, even if the clear is coming off. Honestly, though yes it is dirty, that isn't a bad looking car at all. Okay then...

When you say it still has the MAF, do you mean that it hasn't had the update that converts the MAF just to IAT function? That could very easily be the problem right there (a bad or dirty MAF) if it hasn't been updated... Also, check for vacuum leaks with carb-cleaner or starting-fluid. Check to make certain the vacuum-lines running into your heater-controls are not leaking by using a vacuum-pump.

I am not certain which wires on the MAF act as the IAT, I'm sure someone on here knows for sure, but I think they are the black/yellow and the black/pink wires. The black/light green should be positive voltage in from the MAF relay, black/white should be ground, and black/red is a common sensor ground with the TPS, according to my diagrams.

99.8% of the time, if a coil is at fault, it will have problems on both posts, so plugging a spark-tester into either one should show a result. I like going to the spark plug itself, just so I know there isn't a defective wire in between, and the front three plugs are easier to get to than the coil-pack is anyway.

Your car has remarkably few miles on it, but that may not be a good thing so far as the injectors are concerned -sitting for long periods tend to cause them the gum-up and fail, and even a good injector cleaner may not be sufficient to clean them out -especially if they damaged themselves trying to operate before the cleaner got to them and did its' job. If you can't find anything else, consider pulling the upper intake plenum and removing the fuel rails and injectors (as an assembly). From there, you can put small glass jars under each injector and have someone crank the engine (with a fire-extinguisher handy, just in case) and you can check for proper fuel-spray, atomization, and even make certain all six injectors are releasing the same amount of fuel. This is a rather extreme test, and I don't think you are at this point yet, but keep it in mind. You should still Ohm-check the injectors, the harness plug should be at the back of the intake manifold.

With the pinging, how old is the gas in the tank? Is there water contaminants in it? It may be time to Sea-Foam the car too. You said you did the plug wires, but how old are the plugs themselves? 'Reading' spark-plugs often yields incredible diagnostic insight if they are due for a change.

Hey [i[MoneyPit[/i], any other ideas he should run through??

[88corsica5spd28]

I paid $450 for this car as a project. Cars this old and rust free are rare here, so that and the interior are why i bought it.

As far as the MAF update, I'm not positive, but i don't think so.

As for the plugs, i pulled them (except for #1, it's stripped) and they were a touch ashy but the electrodes weren't that worn so i cleaned them up and put them back in. The PCV valve was missing for an unknown amount of time on this car, so I'm hoping (praying?) that's the reason.

I run through about a tank a week in this car and the symptoms aren't new so i doubt it's bad gas. The pinging comes and goes, it's not constant.

I have a parts motor i could swap the injectors out of so i may do that...

Also: i failed hard putting the pics up, sorry about that.

[Money pit Beretta]

Those MAF's are known to go bad and tend to have a very short life. I'd say clean first, but I'd bet it needs to be replaced. Or you can convert like Rettax3 said, that could save time and money in the long run.
A stripped plug? How bad is it? Did you put anti-seize on all the new plugs?

Dang early.....thinking that is the EGR with vacuum control. Going to have to look that up.
I would think a good steam clean(water sprayed into the throttle body) or Sea Foam down the brake booster hose would help. I'd bet there is a large amount of carbon in that engine. Ok, Sea Foam would be better in this case.
Wow I'm tired.
Any black smoke out the tail pipe when driving or at start up?

[Koots]

With an old, potentially carbon-filled engine, I like to suck clean, mineral-free water through the vacuum hose first (like you would with seafoam), which effectively steam cleans the engine and really breaks things loose.

It is not a solvent though, so Seafoam works great right afterwards (half through intake vacuum, the other through the fuel tank).

Even if it doesn't fix your problem, having carbon build up in the combustion chamber is no longer a worry for you and you can rest easy.

[88corsica5spd28]

Those MAF's are known to go bad and tend to have a very short life. I'd say clean first, but I'd bet it needs to be replaced. Or you can convert like Rettax3 said, that could save time and money in the long run.
A stripped plug? How bad is it? Did you put anti-seize on all the new plugs?

Dang early.....thinking that is the EGR with vacuum control. Going to have to look that up.
I would think a good steam clean(water sprayed into the throttle body) or Sea Foam down the brake booster hose would help. I'd bet there is a large amount of carbon in that engine. Ok, Sea Foam would be better in this case.
Wow I'm tired.
Any black smoke out the tail pipe when driving or at start up?

I cleaned the MAF ~6 months ago just as a precaution.

#1 just spins, it won't come out. It's a very very slight compression leak, I'm pretty sure not enough to cause any noticeable symptoms.

The EGR is indeed vacuum controlled, or it looks to be...

I'll try the water and seafoam after some of this snow melts.

No black smoke any time, no soot in the tailpipe either.

[Koots]

A leaky cylinder due to stripped spark plug could be the issue, or that spark plug hasn't been changed in years because it was stripped and it's causing the misfire/hesitation due to age and deterioration.

[88corsica5spd28]

No offense intended, but as little as it's leaking i seriously doubt that. Since the car only has 60k on it and the other plugs weren't worn out I'm assuming these are the 2nd set of plugs.

Not to mention it doesn't have a dead cylinder, more of a random misfire.

It acts like a vacuum leak but i can't find one.

[Money pit Beretta]

MAF is clean, now on to the Sea Foam or whatever you want to use. The key is to clean the combustion chambers so that there are no hot spots(carbon).
The only thing I was thinking about with the EGR is a vacuum leak. As for the stripped plug I'd get that fixed ASAP. If it's leaking compressed air/fuel/exhaust then it can draw in air. That cylinder will be a bit lean and the computer will take what the O2 is telling it and add fuel.

[88corsica5spd28]

You can only hear the plug leaking when it's cranking... i plan on doing a head swap soon anyway.


I'll steam it when i go to my auto mechanics class tomorrow if the snow has melted.

[Money pit Beretta]

You going to do the 3X00 swap?

Didn't know that you were in school, feel free to remind me of things that I have forgot over the years. Always open to learning new things too(that is why I'm here).

[88corsica5spd28]

Thinking gen 3 heads and intake. I dunno about a 3x00 swap... unless i can get a 3500 on the super cheap. Seems like a lot of money for the whole shebang though...