Join Date: Dec 2015
My Ride: 89 LeBaron 2.5 Turbo
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Stage 5, +40s, etc, going LEAN under BOOST?
About 2 weeks ago I put in a Stage 5, + 40's and 3-bar map in my 89 2.5 Lebaron 5 speed.
It's been really awesome. I love the performance!
First off, I have an LC-1 Innovate wideband installed.
About 5 days ago I swapped the stock fuel pump out for a 225 Walbro. At the same time, I swapped the FPR out for an adjustable one from Accufab.
After I installed the 225 pump, I felt good with going up to 15 psi with my grainger valve. At full boost, she was reading about 11.2 A/F. Felt like a rocket.
The only negatives after the fuel pump swap were
longer cranking to start the motor when cold
and poor fuel economy (like 23 highway when not going into boost---even though A/F was at about 14.7)
That fuel pump stuff is beside the point. My problem now is with the motor going lean!
So yesterday I started up the car and noticed I had a CHECK ENGINE LIGHT on. Flicked the key and came up with #23 -- bad air charge sensor. Drove it to work despite this CEL light. I noticed that as vacuum approached zero, my 14.5-ish idle A/F would drop to about 16 A/F. If I dipped slightly into boost, like I probably just touched 5 psi for a split second to test, the A/F would go even leaner to about 17. Needless to say, I was very careful to stay out of boost until I got home tonight.
Luckily I had an extra air charge sensor, so I swapped out the old, bad one, with the new one. The code went away. But she ran awful! First super lean. Then I gave it some gas and she came to like, idling decently with about 15 A/f. I raised the static fuel pressure from 40psi to 45 psi, and the idle A/F was around 14. Okay, it seemed fine. (If I pulled the vacuum line off the FPR, the pressure would increase and the A/F would go round 12.5)
So I took it for a spin. AGAIN with the going lean with reduced vacuum! At around 5-0 inches of vacuum, she had ~16a/f, and as soon as you dipped into boost, again, on the lean side at around 16-17 a/f.
I took it home and tried unhooking the MAP to see if that was the culprit, but as soon as I did, yup, a CEL came on and the thing got pig rich (9-10a/f) so yes the 3bar seems to be doing its job.
I am super frustrated! Any suggestions?