I would like to see if any one can help
I have a 91 olds cutass supreme with a 3.4 L v6 for about 23 years now it has had a little miss when I was in a stop light . but about 6 months it started to get worse it started having a big miss at idle . then one day the car just stoped . so I took it home and started working on it and got it running and we took it to the dealer . they said it was the injectors , so I replaced them . it ran good for about a day or two then it started again . I have replaced and checked almost everything. I replaced the idle control valve ,throtle position sensor, I checked the fuel system , the pump is fine the presure is about 41 psi . i checked the wires , the coils , and the module .I did check the cat to see if it is pluged but its not .the injectors are new , I get a code every once in a while that says the egr valve . How can I check to see if it is good or not.
so here is what is going on . at idle in park it has a small miss. in drive the miss get worse and when the AC is on it real bad. when you give it a little gas it it goes away , but after a few second it will start missing again . the car eats gas like its going out of style. the exauste smells like its getting to much gas . lately the car seems like it is getting flooded and is hard to start sometimes . in last gear if the rpms drop under 2.5 k the when you accelerate the car has a very bad miss and makes the car shake . the only way is to be real soft with the pedal .


if anyone has any ideas on what I can check and how to check it it would be grateful


Tnak you rjg

Welcome to AF, ok so you spent your money for injectors to correct the miss which is still there?, basic diagnostics, is it a bad plug, wire, coil, low compression? These are the issues to be checked for a misfire. No quick answer, this just requires checking out basic diagnostics. The rich smell is raw fuel from unburned fuel in the cylinder. Check for raw fuel in the vacuum hose at the press. regulator also.

I did check all the basics and they all check out OK , So I replaced the egr valve today but It still has a miss at idle but when you start going its has good power and runs fine so far. so they only thing I have not replaced is the MAP sensor and the oxygen sensor . ( I did replace the O2 sensor about 1 year ago )but since the car seems like its flooding I wonder if its getting bad? If the O2 sensors goes bad would it flood the car out. What would cause the car to flood out ? does any one have any ideas? any help would be greatfull


rjg:screwy:

Hi there rjg.
How can you have a 1991 vehical for 23 years??? LOL
Don't drive it unless you have too, rich condition will damage your engine due to break down of The oil.

??What exactly did you do to it to get it running again after it stopped that day but before you changed the injectors??
??Do you know you have the correct injectors to start with?? Do you have the correct ones now?? new or remanufactured??
(I've never ever seen a running vehical have all 6/8 injectors go bad at once, If all of injectors test out of spec or value the problem is something else that affects the the ECM injector out put. High or low or the fuel delivery system.
Or possibly an electrical short that destroyed them, but its not running at that point.)

??Did the shop have the PROPER DIAGNOSTIC TOOL / SCANNER hooked up??
??What was it?? How do you know it was the correct tool??
??Did you check the coolant temp sender, ?? I Think there are two senders just like the 3.1 , one has a single green wire, that is for the guage only, Totaly seperate from the first is a two wire BLACK AND YELLOW , this one is for the ECM to get its readings.
The guage will read fine so this can be very decieving , if the ECM gets the wrong information.
I dont know the exact value off hand, but a easy way to test it is with an multi-meter set to read ohms of resistance. Remove the sensor and test the resistance across the two pins, use some aligator clips and a jumper wire, place the sensor in a small pan of water and heat the water up on the stove or hot plate to around 190' while you watch the guage on the meter. The amount of ohms should change as the water gets hotter. but needs to be at the values speced in the manual.
Also while you are there, inspect the plug for corrosion and chek that you have 5 volts at the yellow wire with the key on. Use a magnifing glass because you really need to look good at the 23 year old wires OOHH '91 will be 17 year old wires. lol

Hope that helps, I'm guessing that you know how to use a Multi meter.

The tps needs to be set and adjusted so it reads ZERO throttle and WIDE OPEN throttle.
The manual will spec the voltage that coresponds to 0% and 100% or the scanner will just show the %age.
??Did you set it after you replaced it?? very important! You can use the multi-meter.
The IAC valve also needs to set and adjusted use the known good tps and multi-meter but best done with the scanner.

??Did you check the plugs?? are all rich/flooded or just a few ??

A rich condition could ruin your 02 and the converter with enough time. Also very important to change your oil very often when running rich, excess fuel will degrade your oil in the crank case and wash the oil off the cylinder walls, engine wear and damage are certain.

??With fresh plugs, does it run good when its cold?
Does it run good over 2500 rpm and stay good as long as rpms high?
( the ECM will read fuel delivery rate from different tablesbased on the in put from the sensors.)
??"Its Hard to start sometimes" ??when?? cold start? or hot/warm? start?
The Intake Air Temperature sensor values have imput that are involved and can be tested with a hair dryer and a multi meter. The MAP sensor values have imput that are involved and can be tested with a hand vacume pump and the multi-meter.
The problem could also be in the wires and or the connectors.
Guessing is much more expencive than a scanner or a trusted mechanic with the diagnostic tool. Stay away from the stealership:nono: , find a local independent guy who does not have time to look at today. (hint, hint)
good luck.

You said that you started with the basics, #1 check,, Battery connections? voltage ok? alt out put ok? High or low on any of these can cause your trouble. #2 check, all grounds ok? bat/engine , bat/front body, engine/frame, engine/rear body. Corrosion, rusty, loose can also cause your trouble.
Good luck again.

sorry it was supposed to be 2 to 3 years
when it would not start that first time I dont remember how I got it started . but I took it to the dealership they said I had bad injectors . but they also said they where no sure but they would have to replace them to be sure ( but it would only cost 1600 for the dealerships guest )
so I had it broght back and replaced them with reman ones . it rang ok but started missing again .
well i did check everything that i could with a multi meter that I could . everything was within tolerance .
but I did get the car running ok . when it was not running good at some point before i took it to the dealership My wife took the car to amco ( why I dont know ) so they were very nice to her and told her it they could check it . first they said it was the plugs and the wire but . it would be expensive for them to replace them the wires . they replace the plugs and saide that I should replace the wire and see what happens .( they replace the plugs with 5.00 platnuim plugs), all the wire were within specs. well last week i checked the plugs ( Becuse after amco replaced them it was the last thing I was going to check My stupidity) they were gapedbetween 65 to 80 when it should be 45 .
well I did regap them but it is having some of the older problems . it has a small miss but it runs great but sometime when It going down the road it get into finak gear it seams like it has a bad miss and the car shackes bad . you have to let out of the gas and then get back into it and it will be ok .

any ideas on that ?
and it dosent start right away anymore

rjg

Sounds like fuel contamination to me.
These fuel systems get build up in the lines and over time pieces break loose and clog your injectors.

Also did you inspect the injector wire harness when you replaced the injectors ?
This is another known problem which can cause a miss.

and Welcome to AF kst3v3n.