six35

my 91 c2 had just gotten a complete rebuilt and was running perfectly for 1400 miles. then it started idling rough, and sometimes would stutter a bit when cruising at one speed. now, when i give it full throttle, it feels weak, as the revs go up.
i was thinking that maybe one or two of the injectors are going bad.

has anybody had a problem like this? i appreciate any help

springer3

You can pulse individual injectors at the diagnostic plug to locate a bad one. You probably have some fault codes that might isolate the problem for you. How much of a warrenty did the rebuild shop give you? Where are you located?

six35

i am located in el paso, TX, and had the car rebuilt at motormeister in downey, CA. the warranty for is for 6 month or 6000 miles, and since he didn't actually replace the injectors, in don't think that they are covered by the warranty. i am sure he would check them for free, but since there are 1200 miles between us, its not worth taking the car there for something i might be able to figure out myself. i talked to the tech there, and he told me it could be a clogged up injector.
today i checked all the spark plugs, and they all look the same, and fine. but thats probably because it only does it some times. i was going to take out the injectors, and take them to a injector place to have them checked, but if there is something i can do myself, i'd rather try that. how do i pulse individual injectors at the diagnostic plug?

andreas

Eric Kessel

Did you check for any air/vacuum leaks? Also, it could be oil in the intake causing the idle problems..... did it get overfilled recently? If you do a search on rough idle, there are lot's of low cost things to look at........
-Eric
NER/PCA
90 C2

JasonAndreas

You can simulate the system diagnostics and check if the injectors are stuck by using a 9-volt battery. Pull the connector lead off the injector and tap the +- sides (any wire will work, speaker cable, etc.) and if you hear a buzzing sound you know the injectors are not stuck. If you plan to pull the injectors off the fuel rail I would suggest running the car beforehand without the fuel pump fuse. That way you won't have to worry about the cup and half of gasoline that is sitting in the fuel lines & rail just waiting to spill all over your engine. It is also possible to pull the injectors out of the intake manifold while they are still attached to the fuel rail.
The guys that fix injectors all use the exact same piece of equipment to measure flow rate and to clean the injectors and all they do is replace the pintle cap, filter and 2 o-rings. They don't "rebuild" anything so find the cheapest place you can. I've seen the service offered for as low as $12USD which isn't too bad considering that the replacement parts are a little under $5 per injector. You can DIY but at $12/each its almost not worth it (and the filter is a nightmare to remove without the proper tool.)

DerkBarrington

Check the distributors. Do you find that the problem shows up during wet weather or humid days? Take a look at the distributor components for corrosion etc. I had similar intermittent problems and that was the culprit.

six35

when the engine was rebuilt, everything in the ignition system was replaced, so i doubt that it is coming from there, plus, i have only driven in dry weather. but i talked to the guy who rebuilt the engine, and when i told him i would take out the injectors, to have them checked and cleaned, he said to first replace all 12 spark plugs. i told him that i checked six of them (one from each cylinder) and they all looked good, but he said all it takes is one that is not working right, which is not uncommon to happen during engine break in.

what do you think?