Hi guys, I have a few post obd-1 conversion issues that you guys may be able to help me with.

My '91dx (Canadaian) hatch has a D15B in it. It was origionally a d15b2 car, converted to mpfi and running a chipped pr4 ecu with a vafc for vtec activation. I bought an ecu adapter harness and a p28 chipped with a d15b map, knock sensor disabled, but still using a 4 wire O2. All this stuff came from a reputable source. I used a new 4 wire O2 for a '94 Si, and a new distributor for a Z6.

Now for the fun part. The car starts and runs, and it runs much smoother than before under NO LOAD. In neutral its fine. Under load, driving down the road it falls flat on its face if you tromp on the throttle, this is accompanied by an incredibly loud intake tract noise. It seems like the fuel pump is shutting down, or not able to keep up with the volume required. It is a stock pump, but it was fine before I did the conversion. On another note, the car has a B&M adj. FPR on it. Fuel pressure is constant around 40psi at idle and if you rev the engine under no load (neutral) I has occasionally dropped significantly (about 20psi) while doing this. These readings have been taken from the fuel pressure gauge mounted in the banjo bolt at the filter. Do you think I could have a bad FPR or a clogging filter? Could it just be a coincidence that all this started right after I did the obd1 conversion?

I've checked and double checked both cam timing and ignition timing, and both are dead on, the ign timing being set at 16degrees btdc with the timing connector jumped. Pulling the spark plugs after a run show the car to be running lean, yet it smells really rich with black smoke at idle. Another wierd thing is that I have no check eng light on when turning the key from off to run, and I cannot pull any codes from the ecm. I thought that jumping the blue timing connector was the proper proceedure to do so. I've also tried swapping in a P06 ecu just to try it. I know it won't provide vtec, but it starts and runs, allbeit with the same symptoms.

I'm at a bit of a loss here. Not sure what to try next. I'm in a relativley small town, and there is nobody local that has done this swap or conversion before.

I've checked and double checked all my wiring, connections, and the vtec and 4wire o2 sub harnesses from the obd1 adapter harness. Could there possibly be something wrong with the previous dpfi to mpfi conversion? Running on obd0 the car ran well, but was rich at idle and had a slight bog on hard acceleration. I figured this was due to the lousy tune in the PR4 ecu and the bandaid vafc.

One last thing... I have a light show gauge (autometer A/F) and when the car bogs hard the light show pins full red/lean and the light dims out.

Any help at all would be greatly appreciated.

I've posted this on a couple boards in hopes that someone else has enountered something similar.

 

i would say it was either fuel filter or pump needs to be changed. I have heard of those things on the side of the fuelrail (it looks like a mushroom cap where your fuel line goes to the rail) go bad and impeed flow. Definintly a leaning out problem though.
good luck

 

i bet it's your b&m fpr.....search for "fpr" i've read that the diaphragm can take a dump on you.....

 

Defintely a FP problem and probably the pressure regulator. Put the stock reg back on and see if that doesn't fix it. A quick check for the pump is just to pinch the return line shut and see if the pressure guage increases to like 70-80 psi (don't hold it for more than a second or 2) if it doesn't jump up replace the pump.

 

Awsome guys. Thanks so much for your input. I've got a stock FPR on the way. I'll see what happens after that. Another local guy has a new Walbro 255 kicking around from an abandoned project. I'll install that aswell, simply because I planned on it in the future and now is the perfect time.

 

Well good luck