suliot1 Posted December 11, 2004 Report Share Posted December 11, 2004 91 Seville, 4.9 engine - 70,000 miles. Starts and runs perfectly until the engine warms up, then stalls badly on acceleration a few times, then engine light comes on, then car runs smooth. I think it might be going into limp mode or something, because it begins to run very rich after the light comes on. Right after I shut it off, it won’t start again, UNLESS I pull the fuse for the fuel pump, run the starter, put fuse back in, then it starts again (engine light on, of course, if it’s warm). When cold, no engine light, but the process starts all over again. So far - new fuel pump, coil, distributer, plugs & wires, air filter, 2 professional mechanics, and 2 weeks in the shop, 1 rental car. They don’t know. Do you? Link to comment Share on other sites More sharing options...
Scotty Posted December 11, 2004 Report Share Posted December 11, 2004 91 Seville, 4.9 engine - 70,000 miles. Starts and runs perfectly until the engine warms up, then stalls badly on acceleration a few times, then engine light comes on, then car runs smooth. I think it might be going into limp mode or something, because it begins to run very rich after the light comes on. Right after I shut it off, it won’t start again, UNLESS I pull the fuse for the fuel pump, run the starter, put fuse back in, then it starts again (engine light on, of course, if it’s warm). When cold, no engine light, but the process starts all over again. So far - new fuel pump, coil, distributer, plugs & wires, air filter, 2 professional mechanics, and 2 weeks in the shop, 1 rental car. They don’t know. Do you? Check your battery and battery connections closely. I had a bad battery in a 91 Seville and I could start/jump it and it would idle fine, as soon as I started to accelerate it would stall immediately. The alternator alone can not provide enough power for the coils and the power demand exceeds what is available. Have the battery checked for a dead cell.. Link to comment Share on other sites More sharing options...
mike5514 Posted December 12, 2004 Report Share Posted December 12, 2004 it seems like you only have the problem in closed loop there are a no of things going on in that position. oxy senser, maf senser, water temp plus I think the idle air control and the tps. The oxy and water will show a code the others will not. I would start with getting the codes and next disconnect the maf sensor connecter with key off start the car and see if problem comes again. Next I would check the iac. Mike Link to comment Share on other sites More sharing options...
adallak Posted December 12, 2004 Report Share Posted December 12, 2004 You can monitor the voltage on the DIC while driving and accelerating. I would check FPR (Fuel Pressure Regulator) as well. The saddest thing in life is wasted talent Link to comment Share on other sites More sharing options...
Scotty Posted December 12, 2004 Report Share Posted December 12, 2004 I jumped the gun, all I saw was stalling on acceleration... Sorry... What codes are setting? When the check engine light comes on the computer sets a code. See the statement below ENTERING DIAGNOSTICS. Press off and warmer buttons on the DIC and write down the codes and report them here. I attached a page that has some of the codes on it... Mike Link to comment Share on other sites More sharing options...
suliot1 Posted December 12, 2004 Author Report Share Posted December 12, 2004 O2 sensors go rich, but only after the check engine light comes on after warm up and many stumbles. No codes before engine warms up. Thanks for the help. This is getting somewhat expensive. I suspect (hope) something minor. Tomorrow, I'll clean out the throttle body with carb cleaner. Link to comment Share on other sites More sharing options...
Scotty Posted December 12, 2004 Report Share Posted December 12, 2004 O2 sensors go rich, but only after the check engine light comes on after warm up and many stumbles. No codes before engine warms up. Thanks for the help. This is getting somewhat expensive. I suspect (hope) something minor. Tomorrow, I'll clean out the throttle body with carb cleaner. What code do you get when the car is warmed up, (the number)..EO43 and EO45? Mike Link to comment Share on other sites More sharing options...
mike5514 Posted December 12, 2004 Report Share Posted December 12, 2004 Yes I made a error also I said the water and oxy sensor are the only ones to show a code I should have said that they are the only sensors to put a engine in open or closed loop. If im wrong please correct me. In any case dont spend any more money untill you check out the advice you will get on this site. Mike Link to comment Share on other sites More sharing options...
Scotty Posted December 12, 2004 Report Share Posted December 12, 2004 Yes I made a error also I said the water and oxy sensor are the only ones to show a code I should have said that they are the only sensors to put a engine in open or closed loop. If im wrong please correct me. In any case dont spend any more money untill you check out the advice you will get on this site. Mike mike explain the open and closed loop if you would, Mike Link to comment Share on other sites More sharing options...
mike5514 Posted December 12, 2004 Report Share Posted December 12, 2004 When the engine is cold before the water temp switch sends its ok to the pcm and the oxy senser is not warmed, up some of the sensors are not in play yet and the oxy sensor is not in control, this is open loop the engine will run fine but not at its best performance. Once the water temp switch gives its ok and the oxy sensor takes control, the engine is being fine tuned by the oxy sensor. The engine is now in a closed loop. As far as I know codes will not be set untill we are in closed loop. Thence the problem in the first post when the car goes into closed loop the oxy sensor is in play and the car is acting up with the engine light on my first suspect is the oxy sensor but another sensor could be interacting with the oxy sensor and one or possibley (remote) both could be causing the problem. My next suspect is the map/maf sensor this is the easiest the next is the cleaning of the aic/isc valve or replacing it. both these units you can make voltage checks on.Mike Link to comment Share on other sites More sharing options...
Scotty Posted December 12, 2004 Report Share Posted December 12, 2004 Thanks Mike, now I understand Link to comment Share on other sites More sharing options...
Oldgamer Posted December 12, 2004 Report Share Posted December 12, 2004 ...The alternator alone can not provide enough power for the coils and the power demand exceeds what is available... Scotty: Can you explain how alternator has enough power when engine is cold and not enough when engine is warm in that case? How you explain more power demand when you step on accelerator pedal? Some people even disconnect the battery after start, and engine still running fine with or without acceleration (I do not recommend this because it can burn electronic components) Of course, in that case first thing to do is to check the codes. Link to comment Share on other sites More sharing options...
Scotty Posted December 12, 2004 Report Share Posted December 12, 2004 ...The alternator alone can not provide enough power for the coils and the power demand exceeds what is available... Scotty: Can you explain how alternator has enough power when engine is cold and not enough when engine is warm in that case? How you explain more power demand when you step on accelerator pedal? Some people even disconnect the battery after start, and engine still running fine with or without acceleration (I do not recommend this because it can burn electronic components) Of course, in that case first thing to do is to check the codes. Sorry, Its not related to HOT AND COLD, I didnt read the above message fully regarding the problem being related to the engine being warmed up, I noted my mistake subsequently above. The battery problem is related to stalling and accelerating. About 5 years ago I had a weird thing happen to me. I was at a friends house and when i went to start my car it would not start, and I assumed it was because I left the flashers on. Previously when I left my house the car didnt start with authority like it had in the past, but I discounted it. Well the super gave me a jump and I THOUGHT I was on my way, pulled out of the spot, and as soon as I put my foot on the GAS, BAM! It stalled, I had NEVER seen that before. Tried again, and it happed again. I replaced the battery and the problem went away. Bbobynski explained that the alternator alone is NOT sufficient to supply proper voltage/current to the coil and electronics any more. I myself have driven a car without a battery after jumping it years ago, and that is one of the reasons I was stunned by this. But now, without a battery you would not be able to drive the car, the alternator is charging the battery, not supporting the electrical system and it requires the battery to fully do that job. I had NEVER seen a defective battery cause a drivability problem... That was a first.... Link to comment Share on other sites More sharing options...
Oldgamer Posted December 12, 2004 Report Share Posted December 12, 2004 I can admit that with low RPMs and a lot of lights on at the same time or A/C running the alternator has to low power. But it's impossible to charge battery and have battery supporting the electrical system at the same time. What's possible is to have battery for peaks of demand when alternator's power is not enough. I just assuming, but may be it's possible on really lows RPM and headlights on that when you step on accelerator something demands power more. Or may be it happened when you shifted the transmission? Link to comment Share on other sites More sharing options...
Scotty Posted December 12, 2004 Report Share Posted December 12, 2004 I can admit that with low RPMs and a lot of lights on at the same time or A/C running the alternator has to low power. But it's impossible to charge battery and have battery supporting the electrical system at the same time. What's possible is to have battery for peaks of demand when alternator's power is not enough. I just assuming, but may be it's possible on really lows RPM and headlights on that when you step on accelerator something demands power more. Or may be it happened when you shifted the transmission? It was a spontaineous stall as soon as I tried to pull away from curb in gear, and trying to accelerate. BAM stall. It was daytime no lights, no AC. I have tried to search the old site to find bbobs statements but have not been successful.. The battery was not just dead, it had internal problems and would not charge. Link to comment Share on other sites More sharing options...
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