In February '16 I replaced the FPR as it was loping at idle and surging at highway speeds. I just replaced it again last week(5/28) as it had the same symptoms come back. These are LBZ FPR from Merchant Automotive. I have PPEI tunes along with the correct tables for the LBZ regulator.
After changing it the first time idle rail pressure would be 4.2-4.5k when desired was 4.4k. Now after the second time its like 4.1-4.6k at idle. It doesn't lope at idle anymore, but its gotten worse and also both times were still out of spec of +/-.1k from desired.
The first time I changed it, it still surged on the highway or any higher constant speed. I bottle tested it and determined that the FPRV was bleeding pressure. I plugged it and all has been well, until recently. going down the highway at 70mph desired rail pressure will be about 18k or so, but actual will plummet to like 13k then shoot up to 22k then back close to desired. It creates a very noticeable bucking effect.
After changing the regulator a second time the highway surge is much better but it is still there slightly. Its not near as bad as before. Injector balance rates are all under +/-2. I don't think its a bad injector, but I guess it could be as I just had to replace #7.
There have never been codes other than an occasional p0103 for MAF. Could the MAF sensor be bad and need replaced? I've cleaned it several times now with no change. I only get the code maybe at most once a week. The trans is getting pretty bad, its slips in most gears now, and its been limped 4 times. I don't believe that would be my issue either. I've checked all the FICM wiring by the alternator bracket also.
My FASS is running 6-8psi. so that's not it either.
Whats every ones opinion? Weak CP3, injectors, maf, trans, or bad FICM?
I have one datalog where I caught it. It is random when it happens. Yesterday it did it when coming to a stop 1 time. Today it has done it both when coming to every stop and while moving at a constant speed. I don't really know what to test or do next.
When coming to a stop a lot of times it will down shift into 1st, desired rail will be 4.4k but actual will jump anywhere from 3 to 7k, sometimes more. Once I'm stopped actual will be like 4.1-4.6k with no noticeable loping. Then when you go to start moving again it will be unresponsive then it jumps and takes off.
After changing it the first time idle rail pressure would be 4.2-4.5k when desired was 4.4k. Now after the second time its like 4.1-4.6k at idle. It doesn't lope at idle anymore, but its gotten worse and also both times were still out of spec of +/-.1k from desired.
The first time I changed it, it still surged on the highway or any higher constant speed. I bottle tested it and determined that the FPRV was bleeding pressure. I plugged it and all has been well, until recently. going down the highway at 70mph desired rail pressure will be about 18k or so, but actual will plummet to like 13k then shoot up to 22k then back close to desired. It creates a very noticeable bucking effect.
After changing the regulator a second time the highway surge is much better but it is still there slightly. Its not near as bad as before. Injector balance rates are all under +/-2. I don't think its a bad injector, but I guess it could be as I just had to replace #7.
There have never been codes other than an occasional p0103 for MAF. Could the MAF sensor be bad and need replaced? I've cleaned it several times now with no change. I only get the code maybe at most once a week. The trans is getting pretty bad, its slips in most gears now, and its been limped 4 times. I don't believe that would be my issue either. I've checked all the FICM wiring by the alternator bracket also.
My FASS is running 6-8psi. so that's not it either.
Whats every ones opinion? Weak CP3, injectors, maf, trans, or bad FICM?
I have one datalog where I caught it. It is random when it happens. Yesterday it did it when coming to a stop 1 time. Today it has done it both when coming to every stop and while moving at a constant speed. I don't really know what to test or do next.
When coming to a stop a lot of times it will down shift into 1st, desired rail will be 4.4k but actual will jump anywhere from 3 to 7k, sometimes more. Once I'm stopped actual will be like 4.1-4.6k with no noticeable loping. Then when you go to start moving again it will be unresponsive then it jumps and takes off.
