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Problem with engine dying

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  • Problem with engine dying

    I've done a search and while I have learned some things from the threads I've read, I'm still unsure of what is causing my problem.

    My car would sometimes (happened about 6 times in the 9 years I've had the car) cut out while running at highway speed, I would pull over and restart and it would get going right away.
    However yesterday it died twice on separate occasions while stopped at an intersection. When I sensed it was dying I gave it some gas but there was no response and it still died. The first time it restarted after 2 tries, the second time it took about 10 tries before it got going, it would crank but won't start.

    The car also idles rough when totally cold, in the first mile or so from a cold start the engine feels like its gonna die and giving it gas gets no response. Things smoothen out after a mile or so.
    It also has difficulty getting off from 1st gear, more noticable on steep inclines, you have to give it more revs before it gets going smoothly. Its akin to what you would feels if you left the parkbrake on.

    I also get a popping / clicking sound thru the stereo during these labored first gear starts. Read that this could be caused by loose DME ground or loose connections in the DME PCB. How to I check for these?

    My car has a little less than 30,00 miles since it is rarely driven. Fairly new distributor rotor, cap, TB gaskets and new plugs, vacuum hoses and AFM elbow in good condition.

    Am planning to change the ff since they are 17 years old already:

    Fuel pump relay, Main relay, FPR, coolant sensor and 02 sensor.

    May also change: TPS, plug wires and ignition coil.

    If changing the above stuff doesn't help, then I will probably change the 2 fuel pumps too since they have been been replaced. Have cleaned the intank pump intake and changed fuel filter a few years ago and since the car doesn't get much use I don't imagine them being clogged, but will check them out.

    Will also check ground wires behind alternator and the one on the engine. Plus the battery cable in the trunk.

    Anyother stuff I should look into? Any other info to help solve my problem(s) would be greatly appreciated.


  • #2
    I was having a somewhat similar problem with my car dying out of the blue. The coil wire going to the distributor (plug on bottom of distr.) would work loose a little bit enough to break contact. Took some needlnose to that plug end and now it snaps on tight, havent had the problem since. Just something to look at... The ground bolt next to the DME has also caused me much trouble. My car was running extremely rich (getting about 8 mpg, and had ridiculously high CO output), while checking things at the computer i accidentally bumped this ground and it moved freely. Tightened that bolt, now get 20+ mpg and normal emissions. It would be a good idea to check that ground along with the others you mentioned. HTH


    • #3
      Hi. thanks alot for the info. Will check out the coil wire going to the distributor tomorrow.

      Will also check the DME ground wire. Its been a while since I fiddled with the DME so I can't remember where the ground wire is. Will it be visible as soon as I remove the plastic cover behind the glove box door? What color wire should I be looking for? I could have this problem since I've been getting poor gas mileage lately.

      Thanks again.

      Any guys with other ideas, please do chime in.


      • #4
        In general older car problems are very often bad connections between wires, and particularly ground connections where copper meets steel (dissimilar metals). Don't forget to check your battery connections, on the battery and the one where the battery cable meets everything else under the hood.

        If the car is seldom driven, how do you keep the battery up? This could be at least in part a weak battery. If you don't already, try keeping a Battery Tender or similar smart charger on the car. Check the battery water level if it's one where you can do that. Re-reading your original post, a weak battery could just be the main problem.

        I strongly recommend AGAINST changing coil, ignition wires, etc. UNLESS you test them with a meter and find them bad. You can waste a lot of money and time "Easter egging" like that.

        Now to talk out the other side of my mouth, if you have deferred maintenance items like spark plugs, fuel filter, etc. I strongly recommend that you DO change these.

        Look at the thread where the NYC professor chased problems in his car round and round, in the end it was the battery cable under the hood connection that was loose.


        • #5
          Track- Yes you should be able to see that ground bolt when you remove the plastic cover behind the glovebox door. Its going to be just left of the DME, about 20 or so brown wires all ground right there. I also agree with Mitch's point about not throwing parts at the problem, i replaced the O2, Catalytic, and had a shop try to diagnose the issue i was having before i found that loose ground. Expensive lesson. Run through and check (or tighten) any and all grounds, connections, plugs, etc. All it costs is a little time, and may even fix your issue! Happy hunting!


          • #6
            Thanks for the input. However I'm quite sure its not the battery. When my car died the other day it took me about 10 cranks to get it restarted. If it had died because of a weak battery, I dont think it would have lasted 10 cranks. Besides, my battery is hooked up to a trickle charger whenever it is not in use.

            Nevertheless I have checked all battery connections for both +12V and ground and everything is in good order. The only thing I have yet to check is the DME ground.

            Spark plugs are less than 500 miles old, fuel filter is already several years old but with less than 10,000 miles on it. But will change it along with the fuel pumps if replacing the fuel pump relay, main relay, coolant sensor and FPR does not solve my problem. Most of the items I'm replacing are quite cheap, replacing them gives me extra peace of mind, it is a 17 year old car after all.

            May also replace the ignition coil and plug wires too.

            Have borrowed a TPS and AFM and will be trying them out too.

            Thanks for the input, keep em' coming.


            • #7
              Just an update of what has happened to my car-

              I changed the ff parts last month: main and fuel pump relay, FPR, fuel filter, coolant temp sensor and 02 sensor. Have also checked the engine's ground wires and the plug wires.

              Did not notice any change with the engine's idle when I tried tapping on the DME, tugging at its connector and ground wires. Opened up the DME and did not see any broken solder or damaged components.

              Tried out a friend's AFM and TPS, plus my new ignition coil. Put back my own AFM, TPS and my old coil when I did not notice any change with how the car ran with my friend's parts and new coil.

              I thought that I had the problem licked and the car ran fine for about a month.

              Unfortunately, yesterday I could not get the car started. I pull the plugs and they were bone dry despite the fact that I had just cranked the engine about a dozen times before removing them. That plus the fact that while checking for spark (one plug out of the cylinder) there was no fuel smell or mist coming out of the open cylinder gets me suspecting that its a fuelling problem. I remember seeing fuel mist coming out of the open cylinder when I was testing for spark when the car would not start last month.
              I checked for spark and it had spark, so I guess that rules out the sensor on the tranny bell housing. I decide to install my new main and in-tank fuel pump, but still no start. More fiddling with the plugs and stuff plus lots of cussing and it finally starts. It ran fine for the rest of the day. So now I'm thinking it must be one of the fuel pumps and maybe I've finally solved the problem. The car also seems to to run much smoother with the new pumps.

              I tried to start the car earlier today, after about 10 tries I still could not get it started. Had to use my other car to get to work. The car is now at home and I'm running out of ideas on what to check.

              What else can it be? Camshaft sensor? Crankshaft sensor? Any ideas?



              • #8
                Probably the flywheel speed sensor. It tells the ECU that the engine is turning over and that it should inject fuel. These sensors can go bad intermittently.


                • #9
                  Thanks for the info.

                  Do you have the part number for it? Is this the one near the bell housing? If this is the one you are referring to, shouldn't I be getting no spark from my plugs? My friend says his M3 was getting no spark when his sensor died.

                  Did some more testing awhile ago, I'm definitely getting no fuel in the combustion chamber. Plugs would come out bone dry even after repeated cranks, the plugs would have come out real wet with fuel shouldn't they?

                  I unplugged the hose on top of the FPR and cranked the engine, fuel gushed out of the hose. I also held the main fuel pump while a friend cranked the car, I could feel the pump "buzz" a bit so I guess that means its working fine.

                  Anything else could cause the injectors not to inject fuel even if there is fuel being supplied by the pumps?


                  • #10
                    pull the entire fuel rail off, leaving it fully intact. it just pops out. you can then SEE the injectors spraying. might be a good idea to "t" in a mechanical fuel pressure gauge right there at the back of the fuel rail.

                    perform a spark check. basically you pull a plug from the engine and watch it spark across the valve cover.

                    cars need 3 things to run: fuel, spark, compression. running WELL requires more, but your car should start. it's easy to test for those 3 basic things.

                    another thing worth checking is the OBC relay box. i jumpered the two green wires at C104 together. this relay removes power from the coil and main relay (which kills the fuel pumps too). so if a CODE is set or the relay malfunctions, you won't have spark OR fuel. you'll just be bumping the engine over and over and over.


                    • #11

                      check your obc relay under the dash, black box behind the abs brain. there is a connector with a grn/grnred wire in it, pull it and jumper those wires, see what happens,

                      this solved my similar problem

                      pit crew


                      • #12
                        i had a similar problem, it ended being my TPS sensor. the sensor was fine but it was just off set. Maybe check that. when my car was cold it did the same as yours stuttered ready to die out, when it warmed up it ran better. My mechanic couldnt even figure out the problem. The $^$$^%$ fool said i needed new rings so i did that and had the same problem. till i noticed the sensor was off, i tweeked it back and now its all good....
                        1991 M3 10Km
                        1989 M3
                        BEGINS HERE


                        • #13
                          Thanks for the input.

                          I dont think its the OBC relay because I have spark and I'm pretty sure the fuel pump is working since I can feel it "buzz" when a friend cranks the car while I feel the pump. I also pulled the hose on top of the FPR and fuel gushed out of the hose when I tried starting the car.

                          Have checked my TPS and I'm pretty sure its working fine, even tried using my friend's TPS.

                          If one (or both) of the sensors in the bellhousing is bad, will this cause the injectors not to inject fuel when starting the car? I tried checking the connectors of the two sensors located on the firewall last night, the plastic terminals crumbled when I disconnected them. With the broken connectors, I have no choice but to replace both sensors, I hope that will solve my problem.


                          • #14
                            FINALLY got my car started!!!

                            Swapped the position of the two sensors (and their respective connections on the firewall) on the flywheel bellhousing and she started right up on the first try. Swapped them back to their original locations and the car would not start again. I'm now 100% sure I've found the culprit.

                            Would have changed the sensors much earlier but my friend said he was getting no spark when his sensor died. I was getting spark so I figured I had a different problem. I'm curious as to which sensor is defective, weird that the car starts and runs fine even though one of the sensors is obviously defective. Though curiously the car will not start if either one of the sensors is not connected.

                            Will be changing both sensors for peace of mind plus both their plastic connectors have disintegrated anyway. Might have to wait about a week to get another sensor since the local parts shop only has one piece in stock.

                            No regrets about having changed main and fuel pump relays, FPR, coolant temp sensor, O2 sensor, fuel filter plus the main and in-tank fuel pumps since these are almost 18yo parts anyway.

                            Thanks for all the help.


                            • #15
                              Great work! Maybe my bro's M3 will have the same problem soon bec his car sometimes suffer hard starting and felt the same way (starting) when I drove your car least I know where to look first now
                              John A.
                              "If your ship doesnt come in, swim to it..."

                              M3 e30 2.5L | R8 v8 6mt | 996 GT3 mk1 | Integrale Evo Martini 6 | Dallara F303/4 Toms | Defender 90 NAS