@davidf Let's blame fouled spark plugs. If the plugs are fouled no amount of cleaning them will get the engine to run right, and plugs are cheap and easy to swap. I'd put in a new set of plugs and see if that helps. If nothing else, you can send the original plugs in with the engine.
@daviff, I agree with @parsonsj that changing spark plugs is worth trying.
A few years ago I was out on track and the car lost power and started running roughly and didn't want to idle. I tried a bunch of things and ended up bringing it up to Spring Mountain. They methodically went through the engine and the ECU Data and tried changing out the coils, plug wires, tested the injectors, balanced the throttle bodies, checked the TPS, etc.. After several hours of working on the car they discovered that I had a failed spark plug. It looked fine and produced a spark at atmospheric pressure but didn't perform under normal operating conditions. They had never seen an issue like this before.
Can you get the car to run for a while if you give it some throttle? If you can it might be worth using the "Old water bottle" trick. With the engine running spray each of the exhaust primary tubes with water as the engine is heating up. The water will evaporate from the cylinders that are operating properly and it won't evaporate on the cylinders that are not operating properly. The more modern version of this test uses a non contact thermometer. This would point you where to investigate further.
If you break the engine cycle down to it's most basic parts it only needs 1) Compression, 2) Fuel (the proper mixture at the proper time), and 3) Spark (at the proper level at the proper time). Of course in reality there are more things that can affect these things such as intake vacuum, etc.. If the car is running roughly that points to a possible imbalance between cylinders. So if you can narrow down the cylinder (s) that are having an issue it may lead you to the solution.
Also, have you checked the compression? Since the problem started with the previous engine I would think that this would be a lower possibility, but it is possible that some of the rings are not seated properly? Probably a low likelihood but since it is easy to check it is one more thing that can be eliminated.
I am interested in hearing your progress and what you find.
This sounds like one of those fun issues!
If the problem has been with a previous engine and now one this one then we should be able to rule out the engine.
I would also suggest that it isn't a problem a with the fuelling/map if it is consistent with both engines as this cannot change without changes being made to the calibration.
The fact that it runs with more revs/wider throttle indicates that it is most likely a small adjustment that is being affected at idle but isn't so important once under load and higher throttle openings.
Have the injectors been flow tested? New spark plugs is also worth trying but I would assume new with a fresh engine?
Resetting the throttle bodies is a good shout although this doesn't sound like it has worked. Have you bene able to check the balance of the throttle bodies? This is something that could affect low down running and also make it seem like it is running rough.
Assume you are happy that the fuel you are using is good? I have seen Rod's problem in the past with a low level - I think a small dip in pressure will cause an engine cut at low RPM but the pressure is not logged fast enough to see the small dips.
One other thing is battery voltage/charging. Do you have another good main battery to try? Or swap the main and starter. I have seen one recently where the voltage was dropping off enough that an engine would start and die - I think the voltage was dropping off low enough on start that it was effecting ECU/injector operation. We believe that this was actually a faulty aftermarket starter motor that was having a larger than normal draw when cranking.
Doubt I will see anything than yourself but feel free to send me the data to have a look at.
Lots of things to try. I have not had time to look at it since a week ago, so I have not checked spark plugs yet. I had not thought about the fuel, but it is possible that I selected the wrong grade at the track. I do remember going to the pump to add fuel to my cans and that correlates somewhat to the beginning of the problem. I have some other 100 octane that I will try. Battery -- interesting. I have another battery that I can swap in.
I will report back when I have some more info. Thanks again to everyone pm this thread for your help and suggestions.
Rule out fuel. I have another SR3 XX and I swapped fuel between the two. The other SR3 runs fine with the swapped fuel, but the problem SR3 still has same problem.
The problem appears to be getting worse, and I suspect electrical may be the issue.
Probably rule out batteries. I swapped in two good Odyssey PC-545 and fully charged them. The voltage on the steering wheel says 11.9 to 12.2 and flashes red warning low voltage when pressing the ignition button. I had seen this before but I dismissed it. I should have mentioned it, but I just figured it was a low battery that needed to be charged, although I did at various times. But now that I put in two known good batteries, fully charged, and because I see a low voltage warning, it makes me suspect an electrical issue.
I have no idea what to do at this point. I was planning to swap out the coil pack, and if that did not fix it then the throttle body and injectors. Also check the spark plugs. But if the problem is electrical, then that would be wasted effort. Any suggestions on what I should check next, or what this low voltage warning indicates?
I am probably washing the cylinders with fuel, so I don't want to continue swapping parts in the problem SR3, however perhaps I should swap in parts from the bad to good SR3 in an effort to further isolate the problem.
Summary of this long thread:
- The problem began with the original engine at about 43 hours at the track last month. I spent two days at the track with first day engine ran perfect, but problem began in last two of four sessions on second day. I noticed that it would not idle well, so I started the engine by holding throttle, ran for about 15 seconds at 3000-3500 rpm, then it would idle. When I came in, the engine died when I got off the throttle.
- I swapped in new factory engine after the last test days, a couple of weeks ago.
- The problem is that it fires briefly and then dies which appears to be a continuation of the problem at the last test, but is now worse. I have had the engine running for about 30 seconds if I hold throttle at 3000-3500 rpm, but it runs very rough.
- This is an SR3 XX with 45 total hours
- I think I remember low voltage warning at the track last month, but I cannot be sure.
- The engine won't fire every time now, and I have had to turn off the master switch to stop the starter motor. The starter however is cranking the engine well. So the problem seems to be getting worse.
@davidf, I would run the engine long enough to determine if each of the cylinders is heating up at roughly the same rate. You can do this with a non contact thermometer on each exhaust primary or the old school way of spraying each exhaust pipe just down stream of where it exits the cylinder head. You may need to do a few 30 second runs to get it warm enough but that should tell you if you have a fuel or ignition issue at one or more cylinder.
I would also do an inspection to look for any potential vacuum leaks.
Check the air filter to make sure it is not clogged (not a high probability but worth ruling it out).
The next thing I would try is to swap the throttle bodies with your car that is known to be working properly and see if these TBs will l work on the other engine.
Then if you still have no Joy I would swap the coil packs.
I would run the engine long enough to determine if each of the cylinders is heating up at roughly the same rate.
...
You may need to do a few 30 second runs to get it warm enough but that should tell you if you have a fuel or ignition issue at one or more cylinder.
Thanks Charlie for the suggestion however I can no longer get the engine to run without or with additional throttle. Just an occasional brief fire and then it dies. Last week it would always fire and then die, but now only occasionally.
Check the air filter to make sure it is not clogged (not a high probability but worth ruling it out).
Air box and filter is off of the throttle bodies.
Well at least somethings have been eliminated!
If you did not fit new spark plugs on the engine swap I would 100% be doing that before anything else - although it is worth keeping in mind as you say that there maybe another fault but you have now fowled the spark plugs so changing them may improve it but your original fault may still be there. The iridium's will not come back if fowled, even if cleaned up.
I would next be going for swapping coil and leads as they are easy - although these normally cause more issues under load.
After this swap the complete throttle bodies (providing the injectors are the same) and see what that does.
I would not be too worried about bore washing/trying to start repeatedly - just as said above you may fowl plugs and that clouds the results.
OK, so new plugs. I have to head down to Atlanta, so I won't get to this for a few days. (it is a new engine so I assume it had new plugs and was running well at the factory, but I understand that I need to eliminate the possibility of fouled plugs)
What about the low voltage warning? Anything worth chasing down?
Let's call the car that does not run the bad car, and the one that does run the good car to make this a little easier. The bad car is chassis 1351 and has 45 hours total on the chassis, zero or close to it on the new factory engine. The good car is chassis 1372 and has under 10 hours total.
Pictures of the spark plugs from the bad car:
I don't see any indication of fouling.
I put the bad car's plugs and coil pack into the good car; good car runs perfect after the swap, so rule out coil pack and spark plugs.
I am unsure of where to check for vacuum leaks, but given it is a new engine I would guess the throttle body rubbers could be one of the few sources? I installed new rubbers and inspected each for cracks when I installed the new engine.
I swapped ECU from bad car to good car. Good car runs well after the ECU swap, so rule out the ECU.
I think I have one or two more obvious items to swap -- the throttle body assembly with injectors, and the TPS sensor.
I just removed the throttle body from the bad car. I noticed that the injector for number 1 cylinder has about 2mm up/down play in it, whereas the other three do not:
Is this a possible issue -- something that may be causing a vacuum or air leak?
I will test this throttle body in the good car now to see how it runs.
Swapping the throttle bodies did not help isolate the problem. I swapped throttle bodies on both cars. The problem car had the same problem -- fires and dies 1 to 2 seconds later. The good car runs perfectly with the other throttle body.
So, rule out throttle body and injectors.
Summary of everything checked and subsequently ruled out:
- fuel
- fuel pump (it works well)
- fuel pressure
- oil pressure
- batteries
- ECU
- coil and coil wires
- spark plugs
- throttle body
- injectors
- throttle body reset
I have 6 gallons in the tank and this car runs well down to 1 gallon on the track. Never had an issue with low fuel level after we installed the ATL fuel cell fix (different topic).
@rlm-dan I will send you a pm and send you a couple of data files.
Thanks again for suggestions. I hope I did not miss anything but please let me know if I did or you have other suggestions. I did not swap TPS sensors, but the sensor appears to be doing what it should and the data shows up on PTMON and the steering wheel.
I will probably next try to get new eyes on the problem.
I have seen one recently where the voltage was dropping off enough that an engine would start and die -- I think the voltage was dropping off low enough on start that it was effecting ECU/injector operation.
I keep wondering whether I have a similar issue, maybe not due to the starter motor but something else?
I don't have any suggestions but this has been a great diagnostic thread. Hope you're able to get it sorted soon and look forward to hearing what the resolution is.
