Problems with a miss

[fedcop90vette]

I have a 1990 L98 with 92,000 miles on it. I took it out for a drive about 3 weeks ago. When I was heading home the car seemed to be real cammy,a definate hard shake at Idol. I got the car home. The next day I drove the car,as I was driving the car started loosing power,I got the car home again,went to restart it and it would start but as soon as you gave it gas it would stall.
I got the car to the chevy dealer,there were no codes coming from the ecm. The dealer gave it a tune up,new plugs,wires points cap. When he started the car again there was a miss on numbers 1,2 and 8 cylinders. Still no codes. EGR valve checked,o2 sensor checked,cats checked,voltage regulator checked,distribitor checked all working as per specs. Swapped ecm out with one we knew was good,same problem. Fuel injectors checked all good. The car will run but anything over 2000 rpms and it stalls. I have a new eprom on the way,but I seriously doubt its the chip.

Any suggestions?

[Tony B.96LT4]

Doug B from the CCDV had a similar experience. Turned out to be a bad fuel pump and an out of adjusted TPS. Don't know if you put a gauge on the fuel line but that would tell you.

[fedcop90vette]

Thanks Tony B, had a clogged fuel injector,fixed it and I'm back on the road! Thanks for your help!

[TomBates]

Questions: How was the condition found? How was the right injector identified?

I have a 90 that was idling poorly when hot; after tune-up, new EGR valve, new fuel filter, now car barely runs. Vette Shoppe and local mechanic both say the injectors need to be replaced (expensive proposition at over $100 each).

Thanks
Tom

[Norm Clemmer]

Questions: How was the condition found? How was the right injector identified?

I have a 90 that was idling poorly when hot; after tune-up, new EGR valve, new fuel filter, now car barely runs. Vette Shoppe and local mechanic both say the injectors need to be replaced (expensive proposition at over $100 each).

Thanks
Tom

I've often wondered about this subject. The fuel injectors on my aircraft get removed every year at inspection and are cleaned. After they are cleaned the cylinder head temps and exaust gas temps of the cylinders are more even with each other.

I know av gas is leaded and auto fuel is not but I have often wondered if there aren't going to be some negative effects on motors with the corn gas they are mixing into the fuel? I might be pooring money down the drain but that is why I am constantly adding additives to my cars.

Is there any company around that cleans injectors? I would bet yours might have deposits in them that is effecting the spray.

[SLAPSHOT]

Bryner chevrolet offers fuel injection cleaning that works very well. I clean mine once a year along with a fuel filter. There is some very poor quality fuel out and you should not run the E85 fuel if you don't have a flex fuel engine. fuel that we have now has only 10% ethanol and usually won't hurt injectors.

[TomBates]

The injectors were tested and found that only two were within spec anyway, so I ordered Bosch D5B replacements from Five-O online, only $308. Hopefully that will take care of it for now, and I'll keep the injector cleaning service in mind for the future.

Thanks
Tom

[bowtieollie]

Hi Norm,

Yes, there is a company that makes a very reliable injector cleaner.

3M

The fuel pump is disabled, the can is connected to the fuel rail and the contents of the can are run through the engine (in approx 15 minutes).
It returns the injectors to like new performance.

In the interim - using a Techron concentrate (in the fuel tank) will also keep them clean. Its not as aggressive as the 3M product - but will prevent poor performance due to the poor quality fuels we are living with.

The Techron (mfg by Chevron) was originally developed in cooperation with BMW for soft carbon deposit issues they were experiencing in the mid 80's.
It was released for use by others in order to amortize the R&D expense incurred. It comes in a two sizes - 12oz and 20oz containers and should be used in a 1oz to 1gal of fuel ratio. Be careful and verify that you get the concentrate. Techron is also available as a tuneup mix and it is not concentrated (not recommended by me) The label should clearly state "concentrate".

I hope you find this information useful....

[carboman]

Look for the black bottle with the Chevron Emblem on it. Pep Boys stocks it.

[Mike Campbell]

Ask Slapshot because I had a bad tank of (I thought was Mobil but has changed to Bombay gas) and not only had to have my injectores cleaned out but also plugs replaced. NO NOT BUY CHEAP GAS !!!;yn

[TomBates]

The Bosch injectors are installed and the car runs like new again! :)

Now I just hope that all the other stuff done was not completely unnecessary! :rolleyes:

Tom

[bowtieollie]

be careful.... the Techron concentrate and dilute versions both come in a very similar BLACK bottle. Only reading the label will determine the correct chemical desired. It must say "concentrate"......

[carboman]

be careful.... the Techron concentrate and dilute versions both come in a very similar BLACK bottle. Only reading the label will determine the correct chemical desired. It must say "concentrate"......

Yes O Lord and Master of all things automotive related. That's why I posted a picture of the CONCENTRATE. I can't wait for your class on cold fusion and its application in modern day racing:)