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Adjusted AFPR, some problems

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RBurroughs

15+ Year Contributor
173
0
May 31, 2004
Frederick, Maryland
I really need to stop touching my car when its running ok. I decided to check my psi on my gauge and see if it needs to be changed to 43 psi. When i started the car, vacuum off, the gauge read 50psi. So i started turning the screw at the top with vice grips, and no gauge change. I ended up taking the screw out, and then realized it must be the gauge. So i put the screw back in to about where i thought it was, and tapped the gauge with my vicegrips. Gauge went to 60, so I started to adjust the gauge again. As I moved the screw, this time the needle moved accordingly. I set it to 43, and attached the vacuum, the need stayed at 43, i thought it was suppose to drop with vac attached. I rev it up under the hood, and here a pop, not to loud, but not too familiar.

I took it for a test drive, 1st gear boosted normal, 2nd gear it boosts, but doesnt really have the pull I'm used to. EGT's rose pretty quick to about 800 C. I just recently got the EGT working so I haven't watched it too much, but I know fuel it was effects EGT's. Around cruise its usually at 5C and I'm pretty sure its gone to 700-800 before, but not positive.

No weird noises from the engine, no excessive smoke. I dont think the pop could be a headgasket since the turbo doesnt spoll when reving, plus the stutter box limits the rev to 3000, and it wasnt stuttering, so I take it the revving was only to around 2500.

Is DSMLink accurate in reading A/F rations? Would changing the AFPR effect the A/F ratio's. I have so old logs that I could compare to new logs, what should I look for? Maybe get my A/F's back to normal of the old logs? More psi to go up, less to go down.

If the gauge moves accurately, could it still be off significantly?
 
Im sure that after your adjustments that you will have to start from base with your link. Get everything back in order...Why are you adjusting your fpr with vise grips? Do you have a liquid filled gauge?
 
Adjusting the fuel pressure will have no affect on the estimated A/F ratio that DSMLink reports - this value is based on the assumption that your injectors are flowing at their rated value. However, this will only be true if the injectors are seeing their rated fuel pressure. The ECU has no knowledge of your actual fuel pressure - it always assumes it to be correct when calculating injector pulsewidths.

I just wanted to add that for those who are running their injectors at a fuel pressure that differs from factory fuel pressure, the accuracy of the reported A/F ratio can be improved by adjusting the properties for this value. For example, if you have 660cc/min injectors installed but are running them at a fuel pressure greater than their rated pressure, then your injectors may actually be flowing at say 700cc/min. If you go to the properties of A/F ratio, you can enter 700cc/min for the injector flowrate property rather than 660cc/min. This will result in a more accurate A/F value reported by DSMLink for your setup.
 
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