a1320honda

Ok, some basics on the car:
93 civic, 83mm AEBS motor, skunk2 pro 1 cams, brian crower head, Walbro 255 intank, stock lines, PTE 1000's, BDL fuel rail, Full throttle FPR, Stock dizzy and wires, NGK BKR7E plugs gapped at .025, Running 22psi.

The car has been on the same tune for about 6 months. Ive had misfire problems in the past which were always the MSD wires i was running. Changed those and it cleaned up. Now a couple months later, i started picking up a mis again. So i went through and changed wires, cap, coil, plugs, then a whole different dizzy. Nothing changed. But what im noticing, is the longer i drive it, the worse it gets. Like when i first start it and let it warm up, i can pull on it and no miss, but if i drive it for another 5 minutes or so and pull on it again, it breaks up real bad but will still rev, and if i drive on it for another 10 minutes or so after that, its like it hits a wall at 7000ish rpm. The wideband never shows that it leans out, but the plugs look pretty lean. Had the injectors flowed and tested, their within 4% of each other which i was told is on the border of acceptable. The last thing i can think of is the more its running, the hotter the fuel pump gets and falls off. Its a walbro that ive had in 2 cars and is about 3.5 years old. I pulled the stock fuel filter off and the gas that came out of that was a little brown, but not too bad. I blew through it and it seemed to be able to be blown through pretty easy. So im kinda at a loss right now. Motor still compression tests at 170 across the board and is like 5% leakdown in every hole.

So....anyone?

Sorry for the long desription.

inspector01

Try out a fresh wideband. Your sensor may not be perfect, and you may not have your ect or iat compensation for temps perfect so it is throwing off your fueling when it is warm.

HiProfile

How many miles are on that particular wideband sensor? They are intended to be replaced every 10k on a turbo motor, but they will slowly 'die' beforehand. Some will fail completely very quickly, randomly (like any consumer product).

The pump may be an issue, but its unlikely that only boost is impacting it. Pumps run 100% speed in a Honda, 100% of the time. Even with 22psi, you're barely increasing the pressure load by 50%. Its only when you run low and it sucks air that you can overheat the pump.

a1320honda

Its a fairly new sensor, maybe 70 miles on it if that. the car has had the same tune on it and running the same way for a while now. And under normal driving the wideband still reads the same AFR's. And still drives around the same. Its just in boost, the longer you drive, the worse it gets.

VtecCarHauler

It could be a number of things. I have seen similar problems before. Most were solved by playing with plug gaps. Of course all set ups will give different problems. I will list some things that have worked on other cars that I have been around.

- change spark plug gaps. ( < or >)
- try different plug wires ( OEM honda only )
- check to all ground wires
- check timing (if it breaks up when the car is warmer the timing could be a reason)
- do leak down and compression test ( a little coolant may be getting into the cylinders.
- pressure each cylinder with compressed air. Open radiator cap and look for bubbles.


The worst I feel that could have happened is a blown head gasket. If you are using 3/8 ARP studs they have been known to stretch (happened to me but it was the tuners fault). After you figure out the problem I would re-tune.

a1320honda

The plugs used to be gapped at .028, i tried goin down to .025 with no change.
Tried new plug wires
The grounds are all good
timing is good
Leakdown and compression are all good

I will try to look for bubbles with the air compressed in cylinders. But like i said, the longer you drive it, the worse it gets.

093turbo16

iTrader: (2)

I would try a tighter gap. Don't be scared to gap them down in the .020-.022 range.

a1320honda

But why would it be running fine, and then all of the sudden i have to gap the plugs down?

093turbo16

iTrader: (2)

Well did weather change for you?
Get warmer out?
IATs any higher?

Have you logged anything with it breaking up and compare it to any saved logs?

Just try gapping the plugs tighter and see what happens.

a1320honda

i tried gapping the plugs down, no change. And no, the weather hasnt changed, but it was good when it was 40* out and so far has been about 90* and the car was still running fine.

Is it common for walbro pumps to slowly start to degrade? It just weird cause its temp related. I mean i can shut the car off for 20 minutes, and mostly everything is still hot but it will clear up if i pull on it right away, but the longer i drive it, the worse it gets. Ive read about aeromotive A1000 pumps that kinda do the same thing, as they heat up, they loose their flow.

a1320honda

Well...i think it might be the fuel pressure regulator. Pulled out the walbro and put a stock pump in and it wouldnt build any pressure. So i put a stock regulator on it and the walbro back in and added some fual to the map for lower pressure and it pulled all the way through the RPM band. So gotta get my Aeromotive FPR hooked up.