Need help with idling and surging issues...scanner numbers inside
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From: St Simons Isl, GA
Need help with idling and surging issues...scanner numbers inside Just finished a D1SC Procharger install, and I'm having problems with the idle and surging (both at idle and under part throttle). I got my base tune from Frost, and on first startup threw a p0300 code, but haven't thrown any more codes since (this was last week) and there are no codes pending according to the scanner. Fuel pressure is 62 on the gauge, and vacuum is 20 and holding steady. I cannot for the life of me find any vacuum leaks, and I have double and triple checked all the plugs and wires. Mods are in sig, and the base tune was constructed to reflect these mods.
I borrowed a scanner from a friend tonight, and wrote down all the readings. These were taken at full operating temp, and were quite erratic, so I wrote down the range where applicable.
Calc Load: 2.3%
STFT B1: -3.1 to -4.6 (jumps around)
LTFT B1: 0
STFT B2: -5.2 to -7.8 (jumps around)
LTFT B2: 0
MAP: 9.1
RPM: 800ish
Spark Adv: 20-22
IAT: 59
MAF: .882-.951
TPS: 0
O2S B1 S1: .050 - .865 (jumps around a lot)
STFT B1 S1: -5.4 to -7.8 (jumps around)
O2S B1 S2: .440 - .805
STFT B1 S2: NA
O2S B2 S1: .045 - .845 (jumps around a lot)
STFT B2 S1: -6.2 - -9.3
O2S B2 S2: .440 - .825
STFT B2 S2: NA
I am a total newb to tuning, so these numbers don't mean much to me. Anyone see anything that stands out that I need to take a look at? TIA.
I borrowed a scanner from a friend tonight, and wrote down all the readings. These were taken at full operating temp, and were quite erratic, so I wrote down the range where applicable.
Calc Load: 2.3%
STFT B1: -3.1 to -4.6 (jumps around)
LTFT B1: 0
STFT B2: -5.2 to -7.8 (jumps around)
LTFT B2: 0
MAP: 9.1
RPM: 800ish
Spark Adv: 20-22
IAT: 59
MAF: .882-.951
TPS: 0
O2S B1 S1: .050 - .865 (jumps around a lot)
STFT B1 S1: -5.4 to -7.8 (jumps around)
O2S B1 S2: .440 - .805
STFT B1 S2: NA
O2S B2 S1: .045 - .845 (jumps around a lot)
STFT B2 S1: -6.2 - -9.3
O2S B2 S2: .440 - .825
STFT B2 S2: NA
I am a total newb to tuning, so these numbers don't mean much to me. Anyone see anything that stands out that I need to take a look at? TIA.
I would guess you sent your pcm in to Steve? If so, not much you can do til you have HPT. Then I'd get with Steve, send him some data logs, and have him tweak the tune for you and send it back.
FWIW, the 60# injectors can be a pain in the small motors @ idle.
FWIW, the 60# injectors can be a pain in the small motors @ idle.
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From: St Simons Isl, GA
These numbers were taken at idle. And Steve said they looked fine, right in line with what they should be. A friend came over last night and we took some HPT logs and sent them back to Steve, and he's sure I have a vacuum leak somewhere, so I've got to track that down...
...just saw this thread...
The logs I got last night have idle air trims in the -20 g/s area (STITs + LTITs) with IAC counts around 30. The engine is completely internally stock. Other an a bump to the accessory tq table to offset the SC load at idle (7-ish%), all idle airflow tables on the car are stock. This amounts to much more than normal air trim adjustment (x10).
The logs I got last night have idle air trims in the -20 g/s area (STITs + LTITs) with IAC counts around 30. The engine is completely internally stock. Other an a bump to the accessory tq table to offset the SC load at idle (7-ish%), all idle airflow tables on the car are stock. This amounts to much more than normal air trim adjustment (x10).
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From: St Simons Isl, GA
Steve at Frost has been nothing but an extreme help with my issues. He's gone above and beyond what $150 should have bought me, and I recommend his services to anyone. Big thumbs up to Steve...I'll be doing more business with him soon!
I wonder if blower cars might need some change to the
IAC effective area table, to compensate for the higher
before-throttle pressure; the airflow demand -> IAC
steps calculation has to be messed up by that, it has
to be assuming BARO at the IAC inlet but BARO is
probably bogus, picked up as pre-start MAP reading.
If you lock the IAC counts using bidirectional controls,
does the surging cease?
IAC effective area table, to compensate for the higher
before-throttle pressure; the airflow demand -> IAC
steps calculation has to be messed up by that, it has
to be assuming BARO at the IAC inlet but BARO is
probably bogus, picked up as pre-start MAP reading.
If you lock the IAC counts using bidirectional controls,
does the surging cease?
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From: St Simons Isl, GA
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From: St Simons Isl, GA
I'm also going to pull off my PCV/catch can routing and plug the ports on the manifold and valve covers to see if there might be an issue there. The only other thing I changed was tee'ing off of the brake booster line for the boost gauge and bypass valve vacuum source. I'll be checking there (again) as well.
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From: St Simons Isl, GA
Still no luck here. I capped off the entire PCV system, and still the same symptoms. Pulled the rails and injectors out, re-seated everything, bolted it back down...no dice. Checked hoses around the brake booster...nothing. Sprayed every inch of the manifold and hoses with carb cleaner...no difference.
Can anyone think of anything else I'm forgetting to check here? I need to double check the back of the manifold again (hard to get back there, and can't see at all), but I can't think of anywhere else to look. Still pulling 19-20 vacuum... Could anything else cause these symptoms?
Can anyone think of anything else I'm forgetting to check here? I need to double check the back of the manifold again (hard to get back there, and can't see at all), but I can't think of anywhere else to look. Still pulling 19-20 vacuum... Could anything else cause these symptoms?
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From: St Simons Isl, GA
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From: St Simons Isl, GA
Re-checked all the vacuum hoses again tonight...even pulled the pillar pod and checked the line going into the boost gauge...nothing. I am lost here...
When I start the car, the idle is perfect. Really smooth, about 900rpm. As it warms up, the idle falls to about 750-800rpms, and begins to get a little (barely) rough. By the time its at operating temp, I can hear a slight surge at idle...but only like 50rpms or so. It's barely detectable.
As soon as you crack that TB, all bets are off. Hesitation, followed by the rpms coming up to match the throttle position. Tonight it held rpms at 1500rpm for a good 8-10 seconds before it started surging. Then it surges like 300 rpms, down and back up.
Is there anything else besides a vacuum leak that could cause these symptoms?
When I start the car, the idle is perfect. Really smooth, about 900rpm. As it warms up, the idle falls to about 750-800rpms, and begins to get a little (barely) rough. By the time its at operating temp, I can hear a slight surge at idle...but only like 50rpms or so. It's barely detectable.
As soon as you crack that TB, all bets are off. Hesitation, followed by the rpms coming up to match the throttle position. Tonight it held rpms at 1500rpm for a good 8-10 seconds before it started surging. Then it surges like 300 rpms, down and back up.
Is there anything else besides a vacuum leak that could cause these symptoms?
