Hey guys,
Well my IROC seems to have developed a strange engine miss after sitting in winter storage since the beginning of October. The tach even fluctuates a little when revving the engine.....it doesn't move smoothly like it should. I'm thinking that it is electrical by the way the tach is acting. I mean, the tach doesn't jump all over the place, but it definitely doesn't move as smooth as it did before. The miss seems to be all over the rpm range when driving. No check engine light. No weird noises. Does anyone have an idea of where to start troubleshooting? I did remove the cap and rotor, cleaned both, and reinstalled but nothing changed. The car has 44k miles, and has had 22lb injectors put in it as well as an Accel distributor. Other than that it is all stock. Any help would be greatly appreciated! I've also looked around for mouse damage but I absolutely don't see any evidence of that. I didn't know if the coil could possibly act like that??? Thanks in advance!

 

Sounds fuelish. Probably an injector with trash in it. You can probably figure out which one by unplugging them one at a time; the one that makes the least difference is the one that's the most farkled.

I'd suggest popping them all out and soaking em in lacquer thinner overnight, esp if you find a bad one. New O-rings of course, lube them with silicone dielectric grease to install.

Are these the Frod orange-top?

 

I'm not sure what injectors they are. The original owner had them replaced. Getting the injectors out of a TPI engine is kind of a major deal... I will try unplugging them individually and see if I can isolate something

 

Yeah I know, not as easy as some other motors, but complaining about it doesn't change what needs to be done. Gotta do what ya gotta do to what ya gotta do it to, with what ya got to do it with.

It's pretty hard for a symptom like that to be anything else besides injectors, really.

 

I've heard a little popping in the exhaust, too...another reason why I thought it was possibly something ignition related. It seems to be running super rich, too

 

Try some new spark plugs then. I just sort of figured you had already done that.

 

My Z28 305 TPI had a dead miss coming out of storage. I rebuilt the distributor (it was time anyway) with new parts and it was still there. I then figured I'd start with the basics; a new set of plugs and wires fixed the problem. The old ones passed the eyeball test with no damage or cracks. Go figure? Good luck!

 

An ignition misfire will result in a perceived lean condition for which the computer will add fuel erroneously.

GD

 

Did you add any fuel stabilizer before putting it away?

 

I didn't. I filled it clear full of premium. I did just add a bottle of lucas fuel treatment. I'm putting new spark plugs in tomorrow, too. I'm sure it still has the original plugs in it

 

Injectors would be my gut. All my thirdgens have been solid as far as ignition stuff. The only one that was ever picky about ignition was my 3.1L, and it only complained when I changed from platinum plugs to colder standard plugs and then winter set in.

With the ethanol in gas, you really need to use a fuel stabilizer all the time. It just doesn't keep.

 

FIXED! And it was soooo dumb. The plug wire came off of #7 at the plug. I did a little troubleshooting to figure out which cylinder was dead, and started with the plug wire, and there it was dangling under the plug. Snapped it back on, and it runs absolutely perfect.

Ya know, I'm the kind of guy that immediately gets all paranoid at the sign of any kind of trouble with my stuff. Right away I was thinking broken rocker arm, bad injector, hell, anything that wasn't a 2 second fix lol. I'm glad that's all it was!!!

 

Sometimes I should read my own signature.

 

No caption required...

EDIT: The preceding was meant as humorous with no ill intent. We all need a laugh.

 

I should have started there before I cleaned the cap and rotor lol. It didn't really need that done, either hehe

 

Oh, and now the tach moves smooth, too!

 

Good deal! Mine had a slight miss also but after running that gas out and refreshing with 93 Non-Ethanol she has run smooth.

 

That is exactly how I took it

 

Were you as nervous as I was?

I should have probably checked the wires at the plugs before I cleaned the cap and rotor......but how often do ya hear of a wire coming off a plug??? How the heck does that even happen??

 

I was nervous. Not too nervous though as I hope to swap my engine out this summer sometime LoL I keep putting it off I guess because the one in it still runs like a champ. Plugs, wires, cap and rotor were the first things I checked. I went ahead and changed wires. Still had a slight miss so I then assumed it was fuel related as it had sat all winter. Shes running fine now luckily it was just a bit of old gas I guess.