REW Sequential Dyno - very uncommon results

Double_J · 12-20-2009, 10:30 AM

Interesting.... I should have given a bit more info. My engine was rebuilt and running fine. I had brought it in to have new BNRs put in. While there I had them do the fuel pump mod. After it was completed it went on the dyno for a tune. The car was running fine did 4 or 5 runs then all of a sudden it went lean like you mentioned above. They stopped tuning made some adjustments to the car and hooked up a fuel pressure gauge. Tried again and you could see the pressure drop right off at transition. They stopped and we went over the list of parts on the car.

4000km ago the engine was rebuilt, a new supra pump, and fuel filter was put in. They figured it must be the stock FP regulator since every thing else was new.

We put it back on the dyno and things were going well. We picked up right where we left off and did another 4-5 runs then bam it went lean again. This time the car sounded different, and it had lost vacuum. So it was torn apart and rebuilt. It looks like my seals had slightly warped.

There are only a few things I can think of that is causing my FP to drop. My pump, stock FP regulator, fuel filter, wiring, or the fuel temperature sensor - not even sure what that thing does.

Is it possible that I got a bad pump, yea. Is it possible the FP wiring job is not good, yea. Is it possible my fuel filter is plugged, not sure. The shop gave it back to me and I drove it home 500km without incident. Of course I was not pushing the car as I am now breaking it in again. Some people say do disconnect the FP temperature sensor since they do not know what it does and they do not use it.

Do you have any suggestions or how would you go a bout attacking this?

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12-20-2009, 10:30 AM	#39
Double_J The Newbie Join Date: Nov 2009 Posts: 3 Rep Power: 0	Interesting.... I should have given a bit more info. My engine was rebuilt and running fine. I had brought it in to have new BNRs put in. While there I had them do the fuel pump mod. After it was completed it went on the dyno for a tune. The car was running fine did 4 or 5 runs then all of a sudden it went lean like you mentioned above. They stopped tuning made some adjustments to the car and hooked up a fuel pressure gauge. Tried again and you could see the pressure drop right off at transition. They stopped and we went over the list of parts on the car. 4000km ago the engine was rebuilt, a new supra pump, and fuel filter was put in. They figured it must be the stock FP regulator since every thing else was new. We put it back on the dyno and things were going well. We picked up right where we left off and did another 4-5 runs then bam it went lean again. This time the car sounded different, and it had lost vacuum. So it was torn apart and rebuilt. It looks like my seals had slightly warped. There are only a few things I can think of that is causing my FP to drop. My pump, stock FP regulator, fuel filter, wiring, or the fuel temperature sensor - not even sure what that thing does. Is it possible that I got a bad pump, yea. Is it possible the FP wiring job is not good, yea. Is it possible my fuel filter is plugged, not sure. The shop gave it back to me and I drove it home 500km without incident. Of course I was not pushing the car as I am now breaking it in again. Some people say do disconnect the FP temperature sensor since they do not know what it does and they do not use it. Do you have any suggestions or how would you go a bout attacking this?