Thank you very much for the replies I appreciate it:
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Originally Posted by Ronnie's.930
A vacuum leak will do this as well. So you have verified that all intercooling and intake components are tight and leak free? Recently, another guy on here had a similar problem and he ended up finding a hole/split on the bottom of the large rubber "elbow" connected to the output of the metering plate assembly . . .
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We installed brand new multi-layer silicone hoses and re-inspected each and every one of them. Been all through every single line in the engine bay and found them all to be in very good/brand new condition. Also sprayed all the joints to see if the idle speed picked up at all and found no issues.
Quote:
Originally Posted by RarlyL8
What did your AFRs do when the engine starts running badly?
Heat can cause aging electrical components such as relays to momentarily fail. If one of your fuel pump relays is affected that would do it.
You might check all the aging electrical components as racing is a tough environment.
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The car runs a Zork tube with the 02 fitting closer to the turbo exit. The AFR's are steady in the acceptable range when the car is running normally and it goes like a bat out of hell running exactly as it should. Then it falls, stumbles and the AFR falls off the map on the lean side and doesn't read anything. However i'm not so sure the AFR is really getting an accurate reading at that time with all the popping and sputtering out the exhaust.
The car has two Holley fuel pumps that pull fuel from the ATL fuel cell into a canister (the name of it escapes me at the moment) to avoid starving of fuel for hard cornering. I will post a picture below (top left of the first picture). A factory 930 pump then sends the fuel to the rear where it is picked up by the secondary pump at the dog leg. The pumps are hard wired into the car.
Quote:
Originally Posted by mark houghton
Just to add to Brian's comments, if you do indeed have poor electrical connections - particularly to the WUR, that could cause you to develop a rich condition when the car is warm (no power to the WUR would cause it to revert back to cold start enrichment settings). The same could happen if you lost the rear fuel pump relay, since the power from that is what feeds the WUR.
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Thank you for the input. This line of thinking makes perfect sense, however as I hadn't mentioned they are wired in directly when the power is on.
Is there any chance that the WUR itself fails? I took it apart and had a look at it, there was a loose washer inside that i'm assuming was used as a shim on top of the springs to change the flow rate? Anyway I removed the washer and cleaned the WUR out and re-installed it. Same result, car got hot after a few laps and then got into its fits of stumbling.
