cwhite951 Posted June 21, 2022 Report Share Posted June 21, 2022 customers car went 'out of tune' and only runs on 3 cylinders (modded 3.0l 944 turbo, 440tq/480hp at the wheels). This one is driving me nuts. everything checks out OK via diagnositics - cylinder 1 is not firing. tested spark via timing light and firing a plug outside the engine via test mode. Replaced all plugs anyway (cheap), replaced wires, swapped out coil packs (D585 - not so cheap). no change. confirmed injector firing via noid light in test mode and while running (you can disconnect injector one a there is no change in running condition and attach the noid light while running and it flashes). swapped out injectors three times (Siemens 835cc)- no change. Compression check reads OK, took cam tower off and checked cam lobe lift - OK. Almost took the head off to examine the valves but ran a leak down test instead and it was good. put it all back together and runs on 3 still. On a hunch I went into the fuel set up and turned on the individual cylinder correction. playing with cylinder 1 if I add the max 50% adjustment is is close to running well on all four. Since +50% is the max I upped the displacement by 10% and removed 10% from 2-4 cylinders (to get a bigger adjustment to cyl 1). That did not run quite as well by feel/sound so I am guessing that the 50% adjustment to cylinder 1 is close. When I dyno tuned is a couple of months ago I didn't have any of this odd behavior. tuning file and datalog attached (with 50% correction on 1) - any ideas on what the hell is going on? Tim G 06-21-22 r1.pclx PC Datalog - 2022-06-21 11;59;37 am.llgx Quote Link to comment Share on other sites More sharing options...
Adamw Posted June 21, 2022 Report Share Posted June 21, 2022 The best way forward would be to put a 2 channel scope on inj1 & inj2 to compare. Possibly low voltage on the supply side? Or could be something damaged in the ecu - although a failed injector drive will usually hold the injector wide open so it is obvious when the engine fills up with petrol... Quote Link to comment Share on other sites More sharing options...
cwhite951 Posted June 22, 2022 Author Report Share Posted June 22, 2022 Ok, I’ll fire up the old oscilloscope and check. Hard to imagine a voltage issue since it’s the same wire right up to where it splits off for each cylinder. Sure since it’s a 4 cylinder I could use a different driver output if I have to. thanks for the input, this one has been driving me nuts Quote Link to comment Share on other sites More sharing options...
Adamw Posted June 22, 2022 Report Share Posted June 22, 2022 5 hours ago, cwhite951 said: Hard to imagine a voltage issue since it’s the same wire right up to where it splits off for each cylinder. I have seen for example the terminals in the injector plug loose spring tension and fret, then make bad contact. Or a bad crimp, or fatigued wire etc. Quote Link to comment Share on other sites More sharing options...
cwhite951 Posted July 2, 2022 Author Report Share Posted July 2, 2022 OK, thought I had fixed it with a new injector....but its back. I don't think its an ECU / wiring issue but I'm asking anyway - because you are good at diagnosing issues! I replaced the injector again (4th one) and it ran great for 3 test drives. made power, AFR right on and looked like problem solved. turned it off to look at data log and as soon as I started it again you could tell it was rough and running lean on one cylinder. Tried the test I did before - add 50% fuel to cylinder one and it ran much better (while sitting in the garage - didn't want to run it under load). Next test - switched cylinder 1 and 2 injector leads. had to add 50% fuel to injector #2 circuit (now plugged in to injector #1) to get it to smooth out. So that tells me its not an ECU or wiring issue. its a fairly new engine that ran fine for street tuning and dyno testing. I have had the cylinder head off twice and no issues, replaced the head gasket, measured the cam, replaced lifters and it keeps coming back. I cant think of a mechanical issue that adding 50% fuel 'fixes' the problem. Clearly running lean on cylinder one (rough idle with light miss fires if you being the rpms up). The fact that it was fine on a test drive and then immediately rough on the next restart has me baffled. Any good ideas? BTW - when it running rough at idle cylinder one head tube is much cooler than the rest. No egt probes but I can measure the exterior of the tube with an infrared pyrometer. I also checked the intake manifold for straight flange and replace the intake hgastes....no intake leak on cylinder 1 Quote Link to comment Share on other sites More sharing options...
Adamw Posted July 3, 2022 Report Share Posted July 3, 2022 Can you swap #1 & 2 coil, leads and plugs. Have you squirted water all around the manifold, injector holes etc to confirm no leaks? Quote Link to comment Share on other sites More sharing options...
cwhite951 Posted July 4, 2022 Author Report Share Posted July 4, 2022 On 7/3/2022 at 4:22 AM, Adamw said: Can you swap #1 & 2 coil, leads and plugs. Have you squirted water all around the manifold, injector holes etc to confirm no leaks? Yes, 3 new set of plug wires, two sets of coils - always #1 misfire. I used the brake clean squirt at the intake manifold gaskets (very flammable stuff!) with no change. I also pulled the manifold off to look for any other issues, cleaned the flange and changed the gaskets. The odd part to me is that It was running fine, turned it off to read data log and then restated it while still sitting in the seat and the issue suddenly reappeared. It sounds so much like a wiring/ECU/Program issue but it sticks at cylinder 1 when I swap injector leads. I cant come up with a mechanical scenario that comes and goes and can be fixed with 50% extra fuel to cylinder 1 (other than an intake leak on runner 1 which I have searched for quite a few times). BTW - the idle speed returns to normal with the 50% fuel added - if it was an intake leak I would expect a small rpm increase with the added fuel. I have been building engines for 30 years and stand alone for 20....never has something driven me this crazy!!! BTW - it has one other odd behavior - at idle with no other parameter changes (tps, rpm, map) it adds a spike of about .3ms to the injector pulse randomly (every couple of seconds +/-). enough that it is noticeable as not a dead smooth idle. Its annoying but I have spent all my efforts on the main issue right now. Quote Link to comment Share on other sites More sharing options...
cwhite951 Posted July 4, 2022 Author Report Share Posted July 4, 2022 attached are the current base file (with the 50% added) a data log of the idle fluctuations a data log of the engine running fine immediately before the #1 issue (same file but no 50% fuel add) PC Datalog - 2022-07-1 1;54;50 pm.llgx PC Datalog - 2022-07-2 4;45;13 pm.llgx Tim G 07-02-22 r0.pclx Quote Link to comment Share on other sites More sharing options...
Adamw Posted July 4, 2022 Report Share Posted July 4, 2022 5 hours ago, cwhite951 said: BTW - it has one other odd behavior - at idle with no other parameter changes (tps, rpm, map) it adds a spike of about .3ms to the injector pulse randomly (every couple of seconds +/-). This is accel enrichment. Your TPS is bouncing between 0 & 0.2% at idle which means TPS delta is bouncing around a bit at idle - up to around 7%, so set your accel deadband to about 10%. It is probably just electrical noise, but check the throttle cable has free play just in case. I notice in your larger log file the warmup enrichment is still active up to about 90°C, but if I look at the warmup enrichment table in the tune you attached it has zeros there. Also idle was in open loop in the log but it is set to closed loop in the tune. So it looks like that tune doesnt match what was running the engine when the log was taken? With the idle in open loop you have 30deg ign timing at idle which could certainly make some cylinders unhappy. Quote Link to comment Share on other sites More sharing options...
kaptainballistik Posted July 5, 2022 Report Share Posted July 5, 2022 Do a flow test on the injectors, But DO it several times... Look for a injector that's a bit hotter than the others ( Cyl 1 injector would be my suspect....) Only really possible on a flow tester due to teh Fluid volume. Quote Link to comment Share on other sites More sharing options...
cwhite951 Posted July 5, 2022 Author Report Share Posted July 5, 2022 8 hours ago, Adamw said: This is accel enrichment. Your TPS is bouncing between 0 & 0.2% at idle which means TPS delta is bouncing around a bit at idle - up to around 7%, so set your accel deadband to about 10%. It is probably just electrical noise, but check the throttle cable has free play just in case. I notice in your larger log file the warmup enrichment is still active up to about 90°C, but if I look at the warmup enrichment table in the tune you attached it has zeros there. Also idle was in open loop in the log but it is set to closed loop in the tune. So it looks like that tune doesnt match what was running the engine when the log was taken? With the idle in open loop you have 30deg ign timing at idle which could certainly make some cylinders unhappy. I did do some changes to accel and idle. The TPS is noisy and an odd resistance range. I tried it with accel enrichment off and I still get the duty spikes. Still tweaking the idle settings but maybe wasting my time due to the main cylinder 1 issue. I also noticed the warmup enrichment setting (the file I started with was setup that way) was still adding fuel at operating temps and I reduced the warmer settings. I am out of town for the week, But I am still trying to come up with a theory on the big issue 3 hours ago, kaptainballistik said: Do a flow test on the injectors, But DO it several times... Look for a injector that's a bit hotter than the others ( Cyl 1 injector would be my suspect....) Only really possible on a flow tester due to teh Fluid volume. I’m going to send them all out to double check. I Have 8 (it’s a 4cylinder) and I have swapped cylinder 1 4 times already with the same results. Quote Link to comment Share on other sites More sharing options...
Adamw Posted July 5, 2022 Report Share Posted July 5, 2022 1 hour ago, cwhite951 said: I tried it with accel enrichment off and I still get the duty spikes. Will need another log then. It sure looks related to accel fuel in the pic below. Quote Link to comment Share on other sites More sharing options...
cwhite951 Posted July 26, 2022 Author Report Share Posted July 26, 2022 Ok, sent the injectors out for flow test and cleaning. Out of the 8 injectors 5 were out of spec. 800cc injectors were all over the board, several were less than 300cc. After cleaning only 4 came back to spec. Customer says the fuel filter is less than a year old. The seimens injectors do have a built in screen and those were removed and still couldn’t be brought back to proper flow. It was always cylinder 1 that clogged. Any other thoughts? Quote Link to comment Share on other sites More sharing options...
Adamw Posted July 26, 2022 Report Share Posted July 26, 2022 What is the filter? Is it an oem type or a aftermarket/billet type? If it is a billet one with a stainless element it is likely a large micron, not suitable for injection. Quote Link to comment Share on other sites More sharing options...
cwhite951 Posted July 26, 2022 Author Report Share Posted July 26, 2022 Stock Porsche filter. Quote Link to comment Share on other sites More sharing options...
Julien Posted July 26, 2022 Report Share Posted July 26, 2022 Hi mate, I don’t know if it could be related but on my 993 the OBC on the dash uses the injector 1 pulse to get the fuel consumption. If your 944 has this feature you may want to check the loom and maybe take the wire out we’re it is spliced in order to make sure this doesn’t mess with your injection. Quote Link to comment Share on other sites More sharing options...
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