ChromeThunder

iTrader: (2)

Hello fellow forum members,

I have encountered a very frustrating issue with my FD lately. The symptoms are reappearing after a believed fix back in March this year which I will explain in a bit. I’ve searched around but it seems other people had similar issues when going past certain RPM ranges, which is not my case. Please read bellow…

My Mods:
Apexi Power FC
Street port
ARC box intake
Stock IC
Non-Sequential Twins
Greddy Boost Controller Profec Spec II
Stock fuel
3” Downpipe / Stock Cat / HKS Hi-Power Cat back
Koyo Radiator
Running at 12psi
All Emissions removed

Here is my problem, a while back and out of the blue the tach needle jumped all the way to 9k rpm (no change on actual engine revs just indication) a beeping sound went off (sound like the low coolant buzzer) the engine died and it was hard to start up again (engine turns but no start). After several attempts the engine started back up and it never happened again.

Early this year, while driving out of a parking lot and engine fully warmed my car hesitated/bucked (Not the suspension bucking type) for a brief second then same symptoms again and the engine died. This time I tried to start it so many times that the battery started to get weak. During my attempts I used the PFC Commander to Monitor Injector Duty % and noticed I was not getting any numbers at all. Since battery was so weak I had to try jump starting and after three cranks it fired back up (Car was already cold). Changed to a new battery and had alternator and starter benched checked at Auto Zone and they both checked good. That seemed to make the issue disappear…. At the time

Around Late March on my way back from work and cruising at 60mph I noticed car was jumpy and hesitated a few times, especially if I pushed down a bit on the gas pedal. At the same time and erratically the tach needle jumped to red line past 8k (PFC Rev limit set to 8100rpm) and up to the very end while that buzzer sound went off again. My Inj Duty was reading 0 to 0.6 even while pressing down on the gas pedal a little. I dropped my gear to 4th and pulled out the clutch to get it to start/crank back up but it only worked a few times until I lost all momentum and had to pull off to the side. Once again I turned the key all the way back to OFF then to on, engine turned but no staring.

After a few more attempts the car started and drove it home, only 3 miles down the road. Once home I pulled the UIM and checked for damaged wiring, grounds etc... Something obvious. I took Ohm readings at the coils according to the maintenance manual and everything checked well. Is there a diagnostics option or fault/code reading for the PFC?

I connected a Datalogit and looked around but couldn't find anything for that. So I did not mess with anything on there. I also added a new thick ground from the body/strut relay bracket to the engine block right below the coils box. Took it out for a drive and it seemed fine but as before the ghost comes out intermittently. Since then, I have driven it on a daily basis everywhere, cruised around and driven it hard at the ¼ mile track without any symptoms but today it happened again. BTW no mods/work have been done on anything afterwards.

Here goes my theory... It seems like the engine will not put out spark or fuel because "technically" the motor is over-revving according to the tachs indication and as a safety feature the ECU or PFC will not provide them therefore the engine will die. At the same time I scratch my head and wonder what the issue is once the engine is dead and I am at a dead stop. When I try to start again needle and all other indications are normal, it will turn but no start. As for possible causes I know the crank position sensors will keep the ECU from putting out Fuel & spark if they don’t sense a full rev while cranking. Wiring is good on them and one sensor was changed once.

I am getting very frustrated and need help figuring out where to start looking. Sorry for the long post but I’ve tried to be as detailed as possible and I don't know where to look next... Any inputs or recommendations will be extremely welcomed.

Thank you for reading

PS: I was able to record it on video right before it happened on my phone and it shows the needle jumping all the way and the buzzer along with my engine starting attempts. Let me know if you want to see it so I can upload it to you tube or something so you can see it.

Fritz Flynn

iTrader: (263)

IMO: you simply have a nasty electric gremlin which you need to find ASAP before you break the cluster and the fuel pump etc.....

The tach going to 9 etc... has nothing to do with the engine thinking it's running at 9k it's a hard hit from an electric pulse.

The car isn't starting because the fuel pump isn't running.

Check both engine harnesses. Wires and plugs from engine harness to ECU, wires to igniter, wires to fuel pump, wires to battery especially if relocated, wires under fender liners, any modified dash wires etc...etc...

Check any place the harnesses have been modified. Check all your fuses and relays etc...etc....

If you can't find the problem I'd recommend taking it to a shop before something worse happens.

Good luck

ChromeThunder

iTrader: (2)

Thank you Fritz
I will start running Ohm checks on the wiring and going over the harness etc. the car was 100% stock when I bough it 4 yrs ago. I've done almos all it myself and I have not messed with any wiring other than the one for the stereo LOL. I did repair a broken wire before on one of the crank angle sensors which prevented the car from starting but no weird tch needdle symptoms back then.

I must also add that during one of my previous attepts I discovered that the idiot who rebuilt my engine used one of the of the two straight (not 90deg) spark wires on the front ign coils right under the UIM/trottle body It was pinched between the oil filler neck elbow and the UIM. It caused it to shafe thru the insulation. That caused spark to arch and jump into the UIM casing. I re arranged all spark wires properly and re-insulated the wire using rubberized tape (used on aircraft repairs/hi temp etc...) after that it disapeared til now. Thanks again.

I will post my progress as I go

Fritz Flynn

iTrader: (263)

Thankfully it sounds like the car won't have too many if any modified wires but the ark thing certainly could of caused problems and I'd start with replacing the spark plug wires. I'll send you a nice set for 30.