Are these the symptoms of an FPR taking a crap?

For a couple of months I was having problems with my car intermittently bucking when boosting. It was like hitting a wall, it would cut out that harshly - but no CEL and the car would not stall. Also the wideband would read lean when it cut out. The problem seemed to get worse the hotter the car was, eg after half an hour or so of hard driving it would do it more and more often. It would get so bad that it would cut out as soon as it came on boost, even like 2psi.

The car was tuned a few weeks ago and behaved perfectly on the dyno, didn't buck or cut out once. But when driving later that day, we pulled over in a gas station for a few minutes and the temps went up slightly as the radiator fans weren't working. Then we drove off, and the car cut out almost immediately when I boosted. Again the wideband jumped from 11/12 to around 14 while in boost. A compression test afterwards revealed cylinder #3 was down, cracked ringlands. When we revved the engine afterwards, the fuel pressure gauge would show the pressure was dropping.

Now I'm getting the block built and I want to make sure I find the cause of the problem. The general view is that it was a faulty FPR - it was only about 6 months old, blingy style with a gauge on it but no brand. It wasn't cheap (about $200) but not necessarily good quality... they saw me coming I think.

So what is it about an FPR that would make it fail when it gets hot? Is this likely to have been the cause of the bucking? And should I now go for an OEM FPR instead of an adjustable one?

Setup: B18C6 w/Hondata, Walbro 255 intank pump, 440cc injectors, stock fuel rail, 7psi

 

bump

 

could it possibly be the fuel pump?

 

no, the problem started when i had the stock fuel pump, changed to a walbro but the problem was still there.

 

lovely young angela,

If the FPR failed, it would most likely have been caused by a torn diaphragm. Temperature would not have any effect on its function if it was torn.

 

so an intermittent problem could not be explained by a torn diaphram.

Ok here's one for you, maybe related? A few months back, my car suddenly started running on 3 cylinders for no apparent reason. The problem was traced back to the Hondata socketed ECU, looks like an injector driver went down so cylinder #3 injector was not pulsing. (coincidence that its now the same cylinder with cracked ringlands? I know #3 is the weak point but.....)

I swapped to another ECU using a converter harness, and the problem went away. But the Hondata dealer has since tested the ECU and reckons there's nothing wrong with it.

I haven't had the running on 3 cylinders problem since... but I did then start getting this cutting out/running lean problem pretty soon after. I wonder if there's one thing at the root of it all. Maybe related to my injectors? They were new RC 440s, saturated I think so no resistor box used. Could a faulty injector have fucked the first ECU, and now caused piston damage?

Gonna go for bigger injectors anyway, but it'd be good to get to the bottom of this!

But anyway, I'm gonna replace the distributor, dump the fpr, swap the injectors, fuel pump has already been done.... surely there's nothing left which might have been the cause?!

By the way a compression test was done AFTER the ECU failure and was normal, so the damage to the piston had not occurred then.


Modified by angela_itr at 4:44 AM 5/31/2005

 

just post some pics of yourself and then well help ya!

jjust jokin.....and if the fpr fails i would think that the fuel pressure would shoot up and it would run rich......

 

I would also check the injector wiring. Make sure that the wiring on cyl 3 is as robust as the others. Perhaps an intermittent short on #3 wiring that burned up the injector driver? Also, I think the damage was probably done prior to your compression test. It is possible to have good compression on a cracked ring land, if it was just a hairline crack at the time. Then once you ran it hard again it probably let go.

 

yeah good point.... I had to drive like 150 miles home on 3 cylinders, but hoped that if the injector was not pulsing at all, this would be less damaging than if a little bit of fuel was going in and therefore burning really hot. Anyway as you say, I guess its possible that the damage was already done...

Although there was only a couple of hairline cracks on the ringland anyway - that was with 3 months boosting after the ECU failure, and also after Mase had it on the dyno for a couple of hours.

Its a mystery..... will check the injector wiring though, thanks