stumble/stutter at 4000 rpm (FIXED!!!!!!!)
#16
Addict
Rennlist Member
Rennlist Small
Business Sponsor
Rennlist Member
Rennlist Small
Business Sponsor
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Something to think about –
65psi is way too high for a stock system, the stock FPR is a 2.5 bar regulator. You should see approx. 36psi with the vacuum line to the FRP disconnected. The fuel pressure will go up in a linear fashion to the manifold pressure, so with 12psi of boost you should see 48psi – not 65!
This explains the rich readings you are getting. It also explains the misfire and lean reading. If you go too rich the engine will eventually misfire and when it does the oxygen is not being burned and the O2 sensor reads that as a lean condition.
BTW – the picture of the cut wires has got me really interested. Where do the cut wires lead too? They do not look familiar to me (which is pretty odd, I can ID just about anything usually!). The bellhousing bracket is also pretty odd too!
65psi is way too high for a stock system, the stock FPR is a 2.5 bar regulator. You should see approx. 36psi with the vacuum line to the FRP disconnected. The fuel pressure will go up in a linear fashion to the manifold pressure, so with 12psi of boost you should see 48psi – not 65!
This explains the rich readings you are getting. It also explains the misfire and lean reading. If you go too rich the engine will eventually misfire and when it does the oxygen is not being burned and the O2 sensor reads that as a lean condition.
BTW – the picture of the cut wires has got me really interested. Where do the cut wires lead too? They do not look familiar to me (which is pretty odd, I can ID just about anything usually!). The bellhousing bracket is also pretty odd too!
#17
Racer
Thread Starter
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Identified the cut wires. They belonged to the stock fuel injector harness. Fuel injection harness was replaced with a Lindsey Racing harness from last DME zap. As for the suzy homemaker bracket, who knows. I will perform the ole bracket delete kit.
The problem was in the circuit board of the computer. Traced the pins back and found an open to an injector driver and timing control. I soldered one joint and had to add two jumper wires for the other two opens.
Thanks everyone for your help. Much appreciated.
The problem was in the circuit board of the computer. Traced the pins back and found an open to an injector driver and timing control. I soldered one joint and had to add two jumper wires for the other two opens.
Thanks everyone for your help. Much appreciated.
#19
Racer
Thread Starter
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
I'll have to recheck fuel pressure. i was using a a old transmission pressure gauge as that was the only thing i could find with a long enough hose. I was just trying to see if the fuel pump could supply the needed volume.