RevvAutoMD

Car starts quick. Runs. Consistent miss every few seconds, when it does this the injectors are what seem to be cutting. Fuel pressure is constant 42 psi at the rail, when the injectors shut it goes to 45 which makes sense. Car starts and runs normal for a few seconds before this begins. Car starts to bog on throttle input hesitiating, now its sitting st 2500 rpm, constant just started doing that a few minutes ago. Disconnecting tps or o2 has no effect. Fuel dampener was removed.(multiple sources so far say this shouldnt really cause this issue. Oil pressure is good. Checked timing many times. Bypassed dme relay just incase no difference.Its just every couple seconds the dme kills the injectors for a split second, but its completely consistent and seems to worsen. Quick shut of and driveable for a few seconds.Then repeats until this last staying at 2500 thing while still misfiring.

Mods:
M-tune w 80 injectors
super 61 turbo
tial wastegate
bosch 3bar fpr


New:
Valve spring seats
valve springs
valves
decked and pressure tested head
Plugs
cap
rotor
coil
headgasket
waterpump
dme temp sensor
bosch
oil filter housing gaskets
vaccum lines
timing belt
balance shaft belt


Quick vid starting at idling then me holding it around 2500 to more clearly show the noise of the miss when fuel cuts, this was before i left the shop tonight when the car wasnt holding itself at 2500 rpm

RevvAutoMD

301 250 8188 oscar

86 951 Driver

DME relay

CyCloNe!

ohm your crank sensors as well sir with a volt meter, usually I think its 800-1200 is good if I remember correctly.

RevvAutoMD

Ive done the jumpers and everything else, remember the coil has power the dme just isnt grounding it out to fire? Couldnt be the relay stopping spark once bypassed right? And we checked the injectors they are pulsing and we have pressure once jumpered. I will say though without the jumpers im not having my fuel pump turn on either, but that doesnt explain no spark with a powered coil and the injectors are pulsing.


Has to be the DME right?

blown 944

It's probably your speed and or reference sensors.

Tom M'Guinn

Agreed. Check to see if the tach bounces or switches at all when you crank the motor. If not, check the speed and ref sensor connectors at the back of the intake (by the O2 barrel connector) -- peel back the rubber boots and you'll probably find wires that are exposed and fully or partially cracked apart. Poor design, common problem....

RevvAutoMD

Tach jumps well though

blown 944

If the tach jumps it may be the KLR. I can't remember which pins to jump, but you can bypass the klr to make sure. Someone else here might know.

So you have fuel (spray starting fluid to eliminate this as a possibility)
You know for sure you don't have spark (pull a plug wire, use a spare plug and and ground it to know for sure)

I like to know with certainty what is really going on.

RevvAutoMD

yeah we jumpered the klr pins already no luck, checked many times the coil, wires, and plugs, no coil impulses, we did read injector impulses, will just have to check the refernce sensors again

RevvAutoMD

Ok now im second guessing my tach jumping it really barely moves cut the boots off and one seems frayed
, how much should it jump just a tic or should it bounce out far and back. thanks guys

Rogue_Ant

I did a quick video to show the proper tach-bounce:

RevvAutoMD

Damn mine looks like that

Rogue_Ant

If it looks like that, then the DME is trying to fire the coil...

Possible issues could be the ignition coil, cap&rotor, coil wiring, KLR (but you already checked this), alarm.

RevvAutoMD

hate this car for the next few hours lol