'93 3rd gen. Engine rebuilt by Rotary Reliability in Santa Ana, CA approx. 4 years ago. Also new computer fitted and dyno tuning at same time. Only done approx 2500 miles since then and running fine until a few moths ago.

Initial problem was misfiring at low revs until engine warmed up. problem was intermittent and it sometimes started OK without misfiring. Recently it has become much worse and it is also misfiring at higher revs. and engine speed varies at all throttle levels. OK, where do I start looking for the problem? Help strongly appreciated.

Thanks

Dave

 

have you looked into the ignition system any?

 

Hi! Not yet. However, plugs and plug leads were replaced at the time of engine rebuild, so it's unlikely they are the cause, although it is possible. To me, (with little knowledge I might add) it sounds more like fuel starvation. The fuel pump was upgraded at the time of the engine rebuild, so, once again, an unlikely but still possible culprit. Alternatively, maybe the fuel filter, as the gas has been a little lower than normal recently.

 

what ecu are you running? if your running the power fc you could look at the display and see what the injector duty looks like to eliminate it being the fuel system, it sounds ignition related to me though

 

do you have a wideband? when you upgraded the fuel pump did you upgrade the fuel pump wiring ?

 

maybe take it back to RRR for a checkup?

they should know their own work better than anyone, sometimes in trying to diagnose a problem you could make things worse.

 

^Bingo!

Professional shop in person inspection trumps the interweb any day of the week.

Moving to the appropriate section

 

My problems appeared to be from my ignition system but turned out to be the wiring harness that lead to the fuel injectors. it was a crappy connection and caused the injectors to either stick open or closed. If you didn't have the harness checked for continuity between the ecu and connectors then that could be your problem. Also make sure your compression numbers are good. If the car sat for a long time the OMP system (if you have one still) could have drained back or not be functioning properly causing the rotor housings to run dry causing poor compression when warm. Lastly like they said above check back with the shop. If you did already what did you find? Keep us posted, answers help everyone on the forums

 

3rd gen, '93.

Finally I got time take my car back to RRR to address the misfire problem. Just prior to taking it back, the car had been sitting for approx 8 weeks (I was out of town). Amazingly, when I started the car, the engine misfire problem previously discussed herein had completely disappeared and the car ran great! However, out of the blue the Tacho and the Speedo gauges had both stopped working and were permanently stuck at zero RPM and zero MPH respectively. I took the car back to RRR

They checked everything out. Fuses were OK. Wiring not been touched or changed since car was last on road and seemed OK. Eventually they concluded that there was a problem with the driver's main display panel and they removed it and found what appeared to be burn marks on one of the tracks on the flexible printed circuit board located at the back of the panel. They then replaced the panel with a used (but believed OK) panel. That seemed to have fixed the problem, so I picked up the car.

On start-up and driving, the car ran OK. Both gauges seemed OK (no longer at zero), (but I didn't check if the tacho and speedo were accurate just at that point, so that the problem I am now about to describe may have already been there when I picked up the car). After driving a few miles both gauges started "jerking" up and down suddenly and seemingly independently, despite constant engine RPM and car speed. A few minutes later, both gauges went down to zero and stayed there.

I stopped the car, turned the ignition off then restarted and drove the car. Both gauges still at zero.

I stopped the car, disconnected the battery, waited a while for engine/engine compartment to cool down a little, reconnected the battery and started and drove the car. Now both gauges were "working" but Tacho. was too low (approx 50% low) and Speedo. was too high, (approx 60% too high).

Tacho. appears to run non-linear with actual RPM (accurate at idle but flattens off significantly above 2000-3000-RPM) Speedo. seems linear with car speed but reading is much too high - gives reading of 110 MPH at actual car speed of approx. 75 MPH.

I'm intend to take it back to RRR but this seems such a weird problem that I need all the help I can get!

Any ideas anybody?

Thanks

Dave

 

The first thing you should have done is turn around and drive those couple miles back to RRR right then

 

Couldn't! I live 20 miles from RRR and my ride had already left! However RRR is working with me to fix the problem and the car will be back in their shop next week. They have always been very cooperative and responsible in getting things fixed and following up.

Dave

 

...sounds like a short if it fried the 2nd gauge board.