HELP - Extreme lean condition above 4500

red94fiveo

New Member
Apr 12, 2003
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Wichita, KS
Little background here: H/C/I swap was done in april, car ran great at WOT but wouldn't idle at all. Called JMS in may and ordered a chip. Since the ship has gone in the car has idled OK, but now won't make power at WOT worth anything, and it had gotten progressively worse the more I drove the car with the chip in.
Well I got the car dynoed on thursday and found out what the problem was. We couldn't ever make a full run b/c the car would go extremely (Above 20:1) lean at about 4000-4500. Before that it would run fine and the A/F would be great. What the crap is going on?
Here is some more dyno info: timing @ 10*, FP @ 43 w/ vac removed, car was making about 220-230 HP and 300-310 TQ at about 4000 on the various runs before we had to shutdown. Under 3K the car was very rich (~10:1), from 3-4K the car was at about 12 or 13:1 and then right after 4K A/F jumped to above 20:1. This was monitored with a wideband O2 from the dyno, but you can also see it on my autometer A/F guage. The JMS program is as follows: 850 idle, EGR gone, no timing taken out between shifts, WOT is not any richer or leaner than stock.
 
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