I got my car tuned a week ago, very solid tune from respected shop.

I did a hard 1-2 pull a couple days ago and shortly after, I noticed a few misses at partial throttle, light load (cruising in 2nd gear).

I got into low boost (5-10psi), and the car acted fine. Got deeper into boost and noticed my AFR's were not dropping, and then suddenly spiked and went full lean. I let off before it started to miss. The problem really seems inconsistent.

There have been no trouble codes set.

It does have a recently installed Deatschwerks 300LPH fuel pump.

I really would like to check fuel pressure, but I have the stock fuel rail, and am weary of going aftermarket, as it may affect my tune (which is a 350 mile drive)




Thanks for any help!

 

wow ur cold start is all over the place, not tryin to be a dick but i was watchin your wideband it was all over the place...might wanna adjust that, now you sure no vacuum leaks? hoses popped off there nipples? haha

 

The coldstart is not the issue. The car is missing in open and closed loop. It is running out of fuel under load and little to no load.

I am sending the DW300 pump in to get tested. I wish I hadn't thrown my Walbro255 out, so I could test with a known good part.

 

sorry to hear blknblu, ive read some good info on that dw300 pump, but also hearin some stories of people havin issues with them, to start ur best bet would be make sure everything in the fuel pump assy is all properly connected and fastened down.

 

That looks like a pump problem...

 

check to make sure your vacuum hose didn't drop off of the FPR...

 

your a/f does seem to be all over the place and the analog gauge sucks, i got dizzy staring at the gauge moving from one side to the other.

 

I'm hoping so!

That's the first thing I checked, because I actually had my boost gauge plummed into that vacuum line.

Yeah, the AFR is very abnormal. When I get into the throttle lightly, you can see the ratio go full lean and start missing .
When running right, the analog is much easier on the eyes, especially at night. Which is why I disowned the digital gauges.

Thanks!

 

well heres what you can do man, go to autozone or another parts store rent one of there fuel pressure gauges, cuz if im not mistaken one of those kits you can t into the vacuum lines, so disconnect on the t where your boost gauge is tap in the pressure kit to it, put it underneath ur hood to where you can see it by the firewall and windshield, go do some pulls and see if your fuel pressure is dropping hard at wot.

 

It did something very odd today. I took it to my storage unit today, and for the first 1/2 mile of driving it was random misfiring. I could hardly get over 25mph.
Out of nowhere, misfires ceased, and it ran smoothly. I was able to accelerate to the speed limit. I got to my storage, and it was idling pretty smooth, with no misses.

I pulled the fuel pump out, and everything checked out ok externally. Im sending it to Deatschwerks to be tested, just in case.

 

take it back to the shop who tuned you and have them fix it, they will be much more likely to work with you if you havent tried to fix the issue already.

 

The closest shop to me is in your area, which is 350 miles away (one way) unfortunately. I'm sending the pump out tomorrow. I wish I hadn't thrown the Walbro out now, just for testing purposes.

 

Hey blknblu, did you get in contact with us and get an RMA # and form?

 

Yes I did! It is on its way right now.

I hope it is the pump, because I'm not a fan of downtime in the short summer we get here, haha.

 

I have the same exact issue but with the buschar dual fuel pumpers... Its been like that for over 1 1/2 years.