What's your A/F on Overrun?, 'Nother D-Jet A/F Question |
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What's your A/F on Overrun?, 'Nother D-Jet A/F Question |
BeatNavy |
Mar 12 2017, 12:28 PM
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#1
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Certified Professional Scapegoat Group: Members Posts: 2,924 Joined: 26-February 14 From: Easton, MD Member No.: 17,042 Region Association: MidAtlantic Region |
For those with D-Jet, what are you typically seeing for A/F ratio on a medium to hard overrun? Based on what I've read here mine seems too rich - like in 10's and 11's. Once the RPM's drop closer to idle it bounces back up to normal idle A/F ratios. Does A/F on overrun even matter?
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BeatNavy |
Mar 19 2017, 11:06 AM
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#2
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Certified Professional Scapegoat Group: Members Posts: 2,924 Joined: 26-February 14 From: Easton, MD Member No.: 17,042 Region Association: MidAtlantic Region |
I did some more looking around today, and I think my throttle shaft is sticking in the throttle body and not returning the TPS to the idle position fully, especially when the overrun is over 2,000 RPM. As it drops below 2,000 RPM, I get A/F numbers more like idle (~13.5). Not sure if the higher vacuum level at higher RPMs is ever so slightly preventing the throttle plate from closing fully, but I pulled the body and TPS to check it out:
As I understand it, in order to be in the idle/overrun "circuit," there needs to be continuity between where the two arrows are pointing in the picture above - the little arm (where the smaller arrow is pointing, the fuel shut-off switch) and the pin (where the larger arrow is pointing). The middle "wiper arm" also needs too be on the idle trace on the board. The only real difference between idle and overrun is the ECU will shut off fuel delivery at RPM's >~2,000. Is my understanding correct? Even after careful adjusting of the TPS I find there's too much play in the switch/throttle body shaft to reliably ensure continuity unless the throttle is really fully closed. May need to overhaul the throttle body. I'll probably also try plugging off the cold start valve fuel supply to eliminate that as a possibility. |
BeatNavy |
Mar 19 2017, 12:29 PM
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#3
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Certified Professional Scapegoat Group: Members Posts: 2,924 Joined: 26-February 14 From: Easton, MD Member No.: 17,042 Region Association: MidAtlantic Region |
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