AFR Problem.

[KevinC]

So, I went to a dyno day today. Got awesome power (IMO) for what has been done to the car.

BUT, there was a problem. My afr's are out of wack. Attached is the dyno sheet and I'm on the verge of detonation (so the dyno guys say). Starts at 14.5 on the left and to about 12.3 on the right of the graph. What do I need, along with an estimated price, to fix this.

Modifications are cat-back pod and boost pill removal. I was running 95 and was told to go 98 octane, but unsure if that will fix it. Was also told to upgrade my fuel pump.

Discuss..


Kevin

 

[meddler]

Hey Kevin,

I spoke to you yesterday at the meet. I have a blue S15 that was parked up the street. Your S15 is very tidy.

I am no mechanic so feel free to shoot down my ideas, but this is where I would start.

1) Do you have a consult cable? you could plug it in and check to see if there are any error messages and also do a datalog while going for a drive to see if there is anything out of the ordinary.
2) Do you have a boost gauge? it could indicate if you have a boost leak which may be causing it.
3) It could be the fuel pump, but if it was, I would have thought it would indicate a lean mixture at high revs. The only way to tell would be replace it. Also it could be a partially blocked fuel filter as well.
4) It could be the fuel pressure regulator stuck open.

I am sure there are other things, but this is all that comes to mind straight away. Do you have a copy of the service manual? There may be a troubleshooting proceedure for just this problem.

 

[KevinC]

Was nice to meet you yesterday.

I think I'll replace the fuel pump, put in 98 since I didn't expect that much power and then go on the dyno again and see if it gets better.

 

[KevinC]

Would me tapping into the fpr line for the boost gauge cause this?

 

[meddler]

by fpr line you mean fuel pressure regulator line, then yeah maybe.

 

[dcoghlan]

um, you should be running 98 octane all the time. This should help you out a bit, and a fuel pump will give you peace of mind if your old pump is getting lazy.

 

[KevinC]

Thanks guys. I think I know what to do. Will report back in a week or two.