Hey all, Well I just paid a visit to the zed doctor (zed4life) and we've run over my motor and Mark believes I've done everything right in trying to stop this Idle/Misfire. All sensors replaced, new spark plugs, new injectors, new ecu, new connectors, cleaned original connectors, checked vct solenoids, battery voltage and clamps are fine, Idle control is fine, throttle bodies are clean and they don't bind up, they're also balanced, no vaccum leacks, perfect fuel pressure, S2 PTU installed ummm probably more done aswell. So as for mods just for the engine are pod filters, fmic, EVC 4 Boost Controller, 2.5" Exhaust with H pipe, 555cc injectors and 555 chip. I can't remember when the problem began but it was probably a year ago. I had the exhaust, EVC and pods installed before the problem arose and it was some time after I installed those that the problem showed. I've never run over 14psi of boost. I've kept the motor serviced. Done a 100k service on it. I'm out of ideas and am willing to look at anything to try and fix the problem. Mark said my next area to look is to make sure my exhaust isn't some how effecting the engine causing it to misfire/idle rough. Any ideas? Thanks, Marc.
Personally id be looking at the coilpacks and the associated wiring for cracks /shorts/arcing swap them out with some spares (i have a full set of spare ones ) Regards Trev
No it hasn't been tested on an Exhaust Gas Analyser. Where would I go for that? And what purpose would it serve in my situation? I did swap the packs out 1 by 1 to see if I had a faulty one. But I may have more than 1. The problem shows at idle and very low rpms. But if I put the boot into it, I have no misfires (none that I can notice anyway).
Most good mechanical shops will have a gas bench. I have access to one, maybe we could work something out. The gas machine can tell you a few things, but mainly i want to see what the air fuel ratio is doing on idle on each bank. Then we can determine what is causing your miss.
How do you do that Niall? Fitting a wideband to each zorst manifold runner is what I would assume is the only way you could do that
Yeah if you wanted to know each cylinder then thats the only way. But any car with a twin exhaust , even if it has a balance tube will still show a variation across the 2 banks if there is something funny going on. So we want to see the percentage of oxygen on idle, the air fuel ratio. even hydro carbons can give us a few clues. So the wideband or gas bench cant tell us exactly what cylinder it is, but it can narrow it down to which side, and tell us some usefull info. Im thinking by testing each coilpack on the secondary side we can determine which cylinder is off. Thats if it is just one cylinder...... P.S, if i do put it on the gas machine i can log it and screen shot it so u blokes can see
It doesn't seem to be any 1 cylinder. As you can remove a coil pack from 1 cylinder and it will miss. You can put it back on and pull another off and it's still there. Hopefully Mark will pop his head in this thread and reply, he might be able to explain it better.
Have you looked at the fuel dampner? I only fixed a Z not long ago with hunting and eratic idle and this was the culprit. As soon as I removed the vacuum hose from the dampner and fuel came out the issue was clear. Pull the hose off that and the FPR and see if fuel comes out.
I'll try the dampener. Mark and I pulled the vacuume line off the FPR and it was fine but I haven't tried the dampener. I have a pressure gauge in my fuel line, would the dampener being stuffed show up on the gauge (as in make the needle bounce around or something)? As my gauge shows 40psi solid at idle.
Had a misfire at idle only on my work car. It started out as just noticeable and got worse over time. The problem was a coil pack arching through the insulator boot onto the plug. The Ford service manager said this was a common problem, and the fix was to lube the insulator boot with dielectric grease, which they did, and the misfire is gone.
Oh and I have also blanked my EGR. I'll try the dampener and also get some electric grease and chuck some in the plugs.
yeah, ive had this on another car. by scoping the secondary side on each coil pack you can look for irregularties.
You've really got to diagnose the problem before you go throwing any more parts at it. or at lease narrow it down to the fuel or spark side.
That's the problem, if I knew which one it was then it would be fine. But at the moment nothing is showing up.
Well Mark and I had another look today. The fuel dampener is fine, no leaks from it. Ohms tested the coil packs again and they're fine. And bypassed the fuel pump control unit and it made no difference. So that's a few more parts ruled out.
it sounds like a partial missfire which is gonna make it real hard to find, It smooths out at revs doesnt it?
It could still be the fuel dampener or regulator, or even the fuel pump. doesnt cost anything to try swapping in known working units to eliminate those.
It sounds fuel related to me.... if it was spark it wouldn't disappear when you put the boot into it. Have you hooked up datascan to see what your O2's are doing ?
