For the last week my car wants to stumble,almost like a misfire.It does it more when it gets to operating temperature.It does it when idling also. The thing is I'm not getting a code or anything in the computer.I even hooked up my scanner to see if anything popped up when crusing,and it didn't. Aybody have any ideas as to what it may be?This is irritating.

 

Is the engine stock or modified?

 

Stock.It acts like it is misfiring or I have gotten some bad gas. But I know that's not the case.

 

Starting to smell a little gas.Would a fuel pump going bad cause this? Anyway to check it and see??

 

Usually the opti is where you begin to have these kind of problems and the smell of fuel could be a symptom of that.

 

Misfires cause it to run rich. You have to find the cause of the misfire. Sensitivity to heat may indicate a problem with the IC Module. Could also be related to a failing O2 sensor - how old are they? Finally, is there any possibility that you have a major exhaust leak before the O2 sensors?

 

Wouldn't a misfire throw a code? My scanner isn't picking anything up. The O2sensors before the cat are around 2-3 years,the sensors after the cat are the factory installed ones. Not aware of any exhaust leak,I'll check it out though.Where's the IC module? I took it to my mechanic,and it ran perfectly when he drove it,I even rode along .Then it started again.two days later.He stays so busy,it will be a week or two before he can get to it again.

 

The IC Module is mounted on a bracket on the front of the driver's side head, along with the coil.

http://shbox.com/1/coil_loc.jpg

Spend some time on Shoebox's site - he also has a method for spacing the IC Module bracket off the head, to reduce heat soak.

http://shbox.com/1/coil_loc.jpg

If you've got a "stumble", it would indicate an irregularity in the crankshaft rotational speed. Whether you call it a stumble or a misfire, that irregularity should be picked up by the CKP sensor and cause the SES light to flash.

 

You can get pretty far by unplugging sensors which forces the PCM into modes it doesnt normally run in (limp home mode or Speed Density, etc)

Start by unplugging the MAF sensor.. this does two things.. 1 - forces Speed Density mode and I hear it makes the Opti run in low resolution mode which may help if your having opti problems.. so if it runs perfect it could either be the MAF or the Opti

If it still runs like crappo unplug the 02 sensors.. then you'l be running only on the MAP sensor.. see how it runs.. if it runs good then plug the MAF back in and see if it changes.

This is the quickest easiest way I know of narrowing down what's good or bad. (if whatever you unplugged doesnt change anything then you can temporarily move on to the next bad part/sensor.. maybe swap with a friends or just buy a new one if it's cheap enough (such as the ignition module).

Also - misfire's only can be detected on 1996 and newer and ONLY if they are FULL missfire's that occur long enough for the algorithm to pick it up. U can have a partial missfire that is just above the threshold to set a code (my 2005 Dodge ram had a weak cylinder that at idle would feel almost like a missfire.. ended up being a weak power stroke so it was ok, not a full missfire - then it got stolen - Lesson here --> DONT BUY/LEASE DODGE)) or you can have an occasional full misfire that doesnt happen long enough to set a code - I have a saturn with a bum injector wire and it usually takes ~5-10 seconds of full complete missfire for the SES to light.. if it fixes itself in time then no SES light, OR if it's just a partial misfire then it usually wont set a SES light.

 

I'll try it.The opti was replaced about a year ago,I wouldn't think it was bad?

 

I found out that the elbow that runs to the TB has some major cracks and a little piece missing.Could this be the cause of my problem?

 

Wrapped some tape over the hole and so far,so good.

 

Absolutely......try cutting a big *** hole in your chest and running a marathon....

Yeah, I've had a similar issue with my older 95. Found the bellows on the bottom was folded under and FUBAR from me not reinstalling it correctly.

Duct tape works...for a little while.

Keep an eye on it. You don't want that crap getting into your intake.

Good luck,
Ivan

 

Still running ok.Now just have to order a new piece.Anyone know where I can get one for a reasonable price? I have only seen them around $100.00.Thanks

 

Check the part source listed on Shoebox's website. You want the "1LE" version of the intake elbow, without the long dongle silencer tube that makes it difficult to remove and install. Shoebox also has the part # on his site:

http://shbox.com/1/4th_gen_tech1.html