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Discussion Starter · #1 ·
Hey guys playing around with my 95RMS tune and I go it pretty dialed in, but the IAC counts are really pretty low, as in it is almost like someone, i.e. previous owner turned the throttle stop screw a bit, from previous knowledge and my other car, idle should be between 30 and 40 IAC counts, but my RMS is at about 10 at idle. I think that it may be causing a BLM split in these areas, as in the left BLM is always about 6 higher than the right, I have read that the IAC can cause this, but just curious on your guys thoughts. once the IAC follower reached about 40 or so the BLMS even out. Now there is no exhaust leaks or anything like that, and I know that individual fuel trim multiplier can cause this as well. As well as if you put the trans in gear the engine will bog, as well as any load on the motor. I am going to go out and play with it a little today, just curious on your guys thoughts for this.

For the speedo it is weird, the gauge is 2 miles an hour high and the scan tool gauge in free scan or datamaster is about 2 mph low, 225/70/15 tires with 2.56 gear. I have used the tool in tuner cat, which is based on an excel spreadsheet that I got from Alex and Anthony at PCMperformance, but the values between the two don't match. When I did the tune with the tuner cat speedo calc, the speedo was 5 mph off, but with spreadsheet it was only 2 mph off, any thoughts on this?
 

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Mike

I am not a tuner guy but I do know the IAC counts want to be about 32...so if someone did f with the stop screw you could check your TPS volts to see if they are about .67vdc fully closed. i suspect if the stop screw was tampered with than the TPS volts would also be off
 

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Discussion Starter · #4 ·
Thanks Roger, yeah I check the throttle stop screw and it is ok, TPS voltage when closed is .50 or lower. Which isn't the greatest, WOT seems to be a tad low at 4.29, but on another run it was 4.55 so I am not sure, TPS could be loose or something, the throttle body was ridiculously clean when I bought it which makes me think they had it apart. I am going to tinker with it more tomorrow sometime and see what happens, may have the Jeep sold so that is a good thing.

95Wagon sent me something to try for the speedo, so I will see what happens with that as well.
 

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"sounds" like the TB stop screw may have been backed off some or as you said TPS may be f with

given the low TPS voltage and IAC counts with TB blades where they are....would be a quick test to see if the TPS & IAC move closer to spec by cracking the blades open SLIGHTLY
 

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I just basically dealt with the speedo always being goofy. IIRC LT1edit did speedo tables better, and I had used the info out of that.

IIRC IACs should be around 30-32 fully warmed in idle. Don't want anymore than 4.8 volts at WOT, 4.5-4.6 Ideal.

I'd agree with adjusting stop screw out.

You don't have an open air breather on pass side valve cover do you?
 

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Discussion Starter · #7 · (Edited)
"sounds" like the TB stop screw may have been backed off some or as you said TPS may be f with

given the low TPS voltage and IAC counts with TB blades where they are....would be a quick test to see if the TPS & IAC move closer to spec by cracking the blades open SLIGHTLY
Good call I can try that and see what happens.

I just basically dealt with the speedo always being goofy. IIRC LT1edit did speedo tables better, and I had used the info out of that.

IIRC IACs should be around 30-32 fully warmed in idle. Don't want anymore than 4.8 volts at WOT, 4.5-4.6 Ideal.

I'd agree with adjusting stop screw out.

You don't have an open air breather on pass side valve cover do you?
That is what Gerry did for me, he uses LT1Edit to change the scalar tables, I put in this value in my revised tune that I did that I haven't loaded yet. Just trying to fix the split in BLM's first before I load and take it for another run. Attached is a snapshot of the values that freescan logged, it is a compressed version of the run but you can see within that the IAC counts at some points gets down to 9, when looking at the counts once they get up to about 40 ish the BLM's match up. So I think that I am on the right track.
As far as the breather I don't believe so, I had a cracked vacuum line on that side that I fixed, but everything else seems to be secure.
 

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Discussion Starter · #8 ·
In thinking about it though, maybe they had the TPS off, and the blades aren't closing all the way due to this, hence it would cause the IAC counts to drop. The TPS voltage would be close with it like this though if the blades are bottoming out on the TPS internal stop. Just a guess. I just can't see the previous owner trying to dick with the stop, cause usually they are a pain to adjust, I will see what I can come up with tonight.
 

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Discussion Starter · #10 · (Edited)
Yeah I have thought of this as well, but wouldn't my idle be higher than normal with a vacuum leak? But now that I am thinking about it, if there was a vacuum leak it would be going around the "metered" vacuum leak of the IAC causing the idle to be normal but the IAC not to have to be open as much. Am I thinking right? I will do the propane test tonight and see if there is another leak somewhere.
 

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Discussion Starter · #11 ·
Well went out and played with it tonight, someone definitely dinked with the idle set screw on the throttle body that was on it, I had a spare and figured I since I was going to have it off, I would just swap it out and not dick with the set screw, they boogered up the torx head on it anyway, found the EVAP purge solenoid feed line was deteriorated so I changed that out, did the throttle body bypass since I had the lines loose, cleaned the IAC and all that jazz, check TPS voltage with the new throttle body, .64 closed and 4.55 WOT so damn new perfect, started it up and well IAC counts are the same low as hell, BLM's seem to line up a little better now, but I Am going to run it down the road tomorrow and run a scan and see what comes out of it. Think I am getting close, not sure what is up with the IAC. Did check for vacuum leaks with propane and didn't find anything.
 

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Discussion Starter · #12 ·
ran it today after loading speedo information from 95Wagon, (thanks for that:) ) and logged some data, the speedo is still off by about 1 mph, scan tool scalar is off by 4mph, probably doesn't matter, but not sure if the shift points and other stuff is generated using the speed value as depicted for the speedo scalar (scan tool) reference. Any insight to this would be great, I guess I could change the VSS, maybe it isn't putting out a clean value? I have a spare, I don't know.

IAC counts when fully warm are about 5 at idle, not sure what is going on I will figure it out.
 

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...maybe the IAC itself is not operateing right?

at least you ruled out a TB with ? stop screw setting...which did show someone had F'ed with it
 

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OK, you say one MPH .
Based on what ? At what speed?

In my experience speedo signal discrepancies are always percent or factors of.

That is to say if it is 1 mph out at 50, then its 2 at one hundred.

Is your 1 mph at one speed or across the board?
If it is always 1 mph then I would be looking at analog gauge needle placement.

In "the olden days" you needed to get the oddo correct over a speedo test section then if the speedo was wrong you would have to work on the head.

When you say the speedo is wrong, the scan tool reading is wrong, what are you basing this on? GPS , pacing another car?
I see a difference in speed between my Blackberry GPS and my Streets and trips.
Matter of fact, right now, my phone says I am going 1 mph right now sitting at my desk.
 

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Discussion Starter · #15 ·
OK, you say one MPH .
Based on what ? At what speed?

In my experience speedo signal discrepancies are always percent or factors of.

That is to say if it is 1 mph out at 50, then its 2 at one hundred.

Is your 1 mph at one speed or across the board?
If it is always 1 mph then I would be looking at analog gauge needle placement.

In "the olden days" you needed to get the oddo correct over a speedo test section then if the speedo was wrong you would have to work on the head.

When you say the speedo is wrong, the scan tool reading is wrong, what are you basing this on? GPS , pacing another car?
I see a difference in speed between my Blackberry GPS and my Streets and trips.
Matter of fact, right now, my phone says I am going 1 mph right now sitting at my desk.
Hey bud,

Yeah I was thinking that the speedo is off, no big deal really as it is accross the board it looks like, 1 mph high, based on GPS, now the scan tool portion is always at least it seems, haven't had the car really passed 60, but it is 3-4 mph low, speedo is high.

Just weird, I didn't know if it would affect the shift points if the data logging computer is reading MPH low I would figure the PCM is using the same value, I can throw the speedo out of the equation, doesn't matter much for that value. Just not sure on what datamaster or freescan is reading.
 
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