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88 running rich on start-up and misfire afterwards
My 88 with 73K on it started running rich on start-up and may or may not clear up after running for a while. Instead of re-inventing the wheel, I feel confident that a forum member has ran across this problem. I have checked the fuel pressure, thinking an injector may be leaking. has good pressure running and holds good pressure after shutdown. Ck eng light appears and disappears depending on how car is running. I figure that is O2 sensor getting rich signal.
Found thread on injectors of this year being a problem. I'll OHM them out and see what I have.
Any/all help is appreciated.
Last edited by Yellowgreenwood; 07-12-2014 at 02:03 PM.
I have the FSM. I think I set some codes trying to "check it out". Cleared them. Had 14, 43 and 45. Ohmed out the coolant sensor, seems okay. I want to replace it and prom for cooler fan temps, but want it running correctly first. 43 could've come from me "tapping" the injectors to see if they were stuck open. 45 is obviously from running too rich. Going to pull rails and check patterns. I haven't driven it much since buying it last year. It just suddenly started acting up. The plugs are "smoked" it could be sensor, but it doesn't hurt to look at injectors, especially seeing how the car has only been driven 1K miles since 2004, and that has been by me. It would "skip" from time to time but now is too bad to put off anymore.
Looks like from previous posts on other threads, injectors are possible.
code 14 could cause a very rich problem. If infact you had that code I would replace it and also get a new pigtail for it as they seem to go south because of the area there at. be 100% sure when you do the pig tail that you wire it back in correctly or it will drive you crazy
Well, working on pulling the injectors and replacing with FIC bosch. Picked up a sensor, so going to replace that as well. Going to replace thermostat and get prom reset for cooler fan operation. Been putting off doing things I've been wanting to do anyway, but now with it down, might as well.
Well, working on pulling the injectors and replacing with FIC bosch. Picked up a sensor, so going to replace that as well. Going to replace thermostat and get prom reset for cooler fan operation. Been putting off doing things I've been wanting to do anyway, but now with it down, might as well.
At one point my 88 was running so rich that the cats were glowing orange. It turned out to be two bad injectors that were not pulsating as they should but remaining open. Once I changed the set with 8 reman ones for under $250 its been running great. I would also check the cold start injector as well.
OKay, took time away from it because it was driving me crazy! (short trip). I replaced the injectors with Bosch Remans because a leaking injector just seemed too obvious from a car that had set up for about 10 years. Got the FSM out once injector replacement didn't fix it. The part that is driving me crazy is that on one crank up, the car seems fine, then turning off key and restarting it will start to run rich. Another start and it may be fine, maybe not. I unplugged the CSV and car wouldn't start cold. I was thinking a possible CSV leaking until that point. About to dive back into it and use the misfire part of FSM diagnostics. It just seems to load up after running for a bit. Been too long since I played with these cars. Looking into getting the Aldl cable to plug into laptop.
Bought the prom "jumper" from TPI, but haven't installed it yet as I don't want to complicate the issues.
Last edited by Yellowgreenwood; 07-31-2014 at 12:23 PM.
Reason: add info
Decided to start from square one. It seems there is very little exhaust coming out. Not sure if running rich messed up Cat Conv or Cat Conv was the original problem. The two resonators(?) towards the manifolds, do they have anything in them? My factory mufflers have been replaced with some type of silencing tips. They are starting to fall apart. While running about 2500, all sorts of soot is coming out of them. I'l try to post pictures here in a bit. Removed Cat (it looked good), started engine, ran ok until it went into closed loop. started missing and running extremely rich. Although it is running rich, it doesn't set Code 45. The FSM stresses to check ECM grounds, so once it cools, I'll check that and plugs.
No surprise all plugs were soot covered. Checked Fuel Pressure reg line, it is dry. Checked canister lines, all dry. next step is checking grounds.
Last edited by Yellowgreenwood; 08-02-2014 at 05:41 PM.
Reason: more info
okay... this thing is driving me crazy!
gutted cat (just in case), doesn't seem to be exhaust related. Replaced plugs, old ones seemed okay but sooty. Replaced O2 sensor while under car. Cleaned all grounds to engine and one from battery terminal to frame. Started car up still running rich. Fuel pressure seemed a little high. Got ALDL cable out to install TunerProRT. Don't think I have something right because did not show values, will deal with that. HOWEVER, while dealing with that, started car, it ran perfect. Removed ALDL cable still ran fine, fuel pressure gage sits around 35 when engine runs fine. Car ran through closed loop just fine. Cooling fans came on when they should, all was great. Killed car, restarted after 2-3 minutes ran great for a while then started running rough, fuel pressure was sitting around 40. running rich since and on every start up.
Will go back through high fuel pressure FSM chart again tomorrow. Doesn't regulator control fuel pressure or could it be pump related?
The fuel pressure regulator determines what the fuel pressure is.
TunerPro is kind of tricky to get connected. You have to go through a menu and select the port that is being used. I don't remember the details offhand. I recollect that somebody had a little post on how to do it. My good memory and obsessive bookmarking works:
Have you ever seen one that works intermittently? On fuel testing, I've gone from pressure immediately dropping off (pulled sending unit and everything looked fine) reinstalled unit and no longer drops off but now when misfiring, fuel pressure is a little high. still no fuel in vacuum line to regulator.
Somebody posted a thread on defective fuel pressure regulator diaphragms several months ago. It seems that the center part of the diaphragm has to be perfectly flat and smooth or it will cause problems.
OKay, taken a few days off on this. Crazy thing. Fuel pressure can be a little high on the "acceptable" side and car runs like crap. If fuel pressure is on low side of "acceptable" car runs great. Of course still getting Code 45.
Can't see how a fuel pressure regulator can be intermittent.
Strange thing is radiator fan comes on while cold. Found another thread on here and guy found out it was ECM.
HELP!!!!
Ok, got scan to work. Still wanting more parameters, but some things came up. ECM Coolant temp has to be way off. It was reading above 252F and engine was cool and dash read 170-190. Disconnected plug, one time it didn't drop, one time it did and read fine. May be pigtail related like was mentioned earlier, but I grounded out terminals and it shot up to 300*. Remove jumper and it stayed above 200*. Also moving TPS with pedal, it would change coolant temp readings drastically. Car is still running like crap even when coolant temps are in specs.
Surely, in 27 years someone else has had this issue.
Did you see the posts about a short in the injector wiring? With temperature changes and movement from a running engine it could be intermittent.
Vacuum leaks, allowing unmetered air into the intake can cause the ECM to try to compensate by enriching the mixture. Check vacuum while running and spray a rough runner's vac lines to search manually.
I'd want to run the test for plugged CAT(s), too. Extended rich running can ruin them.
BTW, I have cleaned an O2 sensor with a propane torch as a temp measure.
Last edited by whalepirot; 09-14-2014 at 12:13 AM.
with what you are telling us, I'd head straight to the inj harness on each side and start it and then wiggle the harness and observe the results. It may be as simple as a change in the tone of the engine as it idles..may stall it, might cause it to smooth out.
Do this with particular attention to the harness on the driver side as it falls behind the valve cover to merge with the trunk line on the firewall.
THAT is notorious for problems due to the cheesy splices in the harness protected by a wrap of black tape (that's factory!) and that area seems to have more wire insulation cracking and breaking allowing cross signaling to occur. Knowing that your TPS, TEMP and all the Inj wires are ALL in the same bundle....I'd almost bet the farm that your problem IS IN THERE !
Pull that harness and listen to the engine. Tug on it, wiggle each inj plug and twist and bend the harness. You'll get some kind of response.
I found a chronic misfire that moved from one cyl to another (1,3,5 or 7) and took MONTHS to track down. The driver side inj harness had bad wire and I accidentally tugged on the right place while the engine was running and suddenly it smoothed out and the misfiring went away! I had been looking at sensors, the ECM, inj and everything else. Had not even thought of wire being faulty.
To do the repair I had to solder in ALL new wire and install all new plugs, from the firewall to everything on the driver side, sensor plugs/wire, all the injectors, everything. ALL the wire was replaced and I double insulated everything. That ended the mystery misfire that had been there off/on for many months....
Odd thing was the passenger side wire looked like new. Not a piece, a section anywhere has a single crack or spot of corrosion on the wire. Only the driver side inj harness....
When looking at fuel problem, I might've had that in ADDITION to this miss/misfiring. the car was slow to start unless I let the pump cycle.
I just can't understand how the fuel pressure being low the car ran fine. When all this started, I had a code 14 so I replaced the sensor while I was changing out the thermostat to prepare for a chip that would turn on the fans at lower temp (haven't touched ECM, yet).
When I went to test fuel system, it built up fine but dropped off once pump stopped. Opened up fuel tank and eliminated the pulsator. Fuel pressure went to normal specs. Problem was still intermittent.
Looked at scan today before starting. Coolant temp showed 182*. Depressing gas pedal TPS and coolant temp changed drastically. Of course you HOPE the TPS will increase as you depress. Started engine and water temp reading was above 200* while dash still read low.
Writing this as I allow engine to cool completely and try moving harness.
Thanks for working with me through this.
Originally Posted by leesvet
with what you are telling us, I'd head straight to the inj harness on each side and start it and then wiggle the harness and observe the results. It may be as simple as a change in the tone of the engine as it idles..may stall it, might cause it to smooth out.
Do this with particular attention to the harness on the driver side as it falls behind the valve cover to merge with the trunk line on the firewall.
THAT is notorious for problems due to the cheesy splices in the harness protected by a wrap of black tape (that's factory!) and that area seems to have more wire insulation cracking and breaking allowing cross signaling to occur. Knowing that your TPS, TEMP and all the Inj wires are ALL in the same bundle....I'd almost bet the farm that your problem IS IN THERE !
Pull that harness and listen to the engine. Tug on it, wiggle each inj plug and twist and bend the harness. You'll get some kind of response.
I found a chronic misfire that moved from one cyl to another (1,3,5 or 7) and took MONTHS to track down. The driver side inj harness had bad wire and I accidentally tugged on the right place while the engine was running and suddenly it smoothed out and the misfiring went away! I had been looking at sensors, the ECM, inj and everything else. Had not even thought of wire being faulty.
To do the repair I had to solder in ALL new wire and install all new plugs, from the firewall to everything on the driver side, sensor plugs/wire, all the injectors, everything. ALL the wire was replaced and I double insulated everything. That ended the mystery misfire that had been there off/on for many months....
Odd thing was the passenger side wire looked like new. Not a piece, a section anywhere has a single crack or spot of corrosion on the wire. Only the driver side inj harness....
07-12-2014, 01:28 PM
88 running rich on start-up and misfire afterwards
