Normal fuel trim, MAP, MAF readings? XJR
#1
Normal fuel trim, MAP, MAF readings? XJR
Hello, I'm trying to troubleshoot a hesitation under mid-throttle acceleration on my 2002 XJR, so I took it for a drive with my Ultragauge hooked up to display the MAP reading, MAF flow, and fuel trims.
The absolute manifold pressure reads 14.65 PSI with the engine off. It reads 6 PSI at idle, even lower on overrun, and around 12 PSI under mid-throttle, which is where I have the hesitation. I read online that 17 to 20 inches Hg of vacuum is normal at idle, and I have about 17.3 by my reckoning. Is that normal?
The fuel trims are varying from -4 to zero at idle, and from 2 to 10 under load. Long term trims are reading about 8. Both banks are quite similar.
The MAF flow is about 6 gm/s at idle, and I saw up to 50 when accelerating.
Does this all seem normal?
Further to my earlier thread, I took it for a drive with a fuel pressure gauge hooked up, and it was around 38 PSI, rising a little under load.
The absolute manifold pressure reads 14.65 PSI with the engine off. It reads 6 PSI at idle, even lower on overrun, and around 12 PSI under mid-throttle, which is where I have the hesitation. I read online that 17 to 20 inches Hg of vacuum is normal at idle, and I have about 17.3 by my reckoning. Is that normal?
The fuel trims are varying from -4 to zero at idle, and from 2 to 10 under load. Long term trims are reading about 8. Both banks are quite similar.
The MAF flow is about 6 gm/s at idle, and I saw up to 50 when accelerating.
Does this all seem normal?
Further to my earlier thread, I took it for a drive with a fuel pressure gauge hooked up, and it was around 38 PSI, rising a little under load.
#2
I'm chasing the same problem with a 2002 XKR100 Coupe. The car accelerates quickly then all of a sudden holds back. Full throttle seems to override the problem but I think I'm about 90HP short. I bought an Auto Engenuity program , but the new laptop promptly died. I want to check fuel pressure at full load, so how do you check this? Thanks....AT
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