scanmaster questions for tuners

[GNocide]

just a couple for the experienced from the not so experienced.

1 ) car idles high at 1400 rpm hot(fuel pressure is at 48 lbs- i thought that would be a cause of increased rpm- maybe not/)60lb injectors btw

2 IAC IS At -0 at idle hot= not 10-20 like the turbo tweak and other guidelines say it should be.
it does move all over with normal driving and boosting.
bl is at 122 during idle hot - also moves to 128 to 133 driving

3) are these two issues related?

thanks for any help and suggestions.

 

[87-WE2]

just a couple for the experienced from the not so experienced.

1 ) car idles high at 1400 rpm hot(fuel pressure is at 48 lbs- i thought that would be a cause of increased rpm- maybe not/)60lb injectors btw

2 IAC IS At -0 at idle hot= not 10-20 like the turbo tweak and other guidelines say it should be.
it does move all over with normal driving and boosting.
bl is at 122 during idle hot - also moves to 128 to 133 driving

3) are these two issues related?

thanks for any help and suggestions.

I'm not super experienced, but your issues could be related to each other. What is your TPS reading on the scanmaster with key on, engine off?? If your TPS is too high, the. It could affect idle speed.

Check TPS when engine off. If .40-.46, then....
Check TPS and iac readings at hot idle.
If readings are outside of the recommended range, you'll have to adjust.
Remember to adjust iac first, then TPS. Adjusting iac affects TPS.

 

[GNocide]

tps is 44 key on or hot the same

 

[87-WE2]

tps is 44 key on or hot the same

Check all lines for possible vacuum leaks. Check all air intake plumbing for leaks or disconnected lines. If no good there, adjust your iac. After iac adjustment, set TPS back to within range.

Sounds like a vacuum leak or air intake leak though.

 

[GNocide]

okay
ill start with the intake plumbing

 

[trixdout]

I'm not super experienced, but your issues could be related to each other. What is your TPS reading on the scanmaster with key on, engine off?? If your TPS is too high, the. It could affect idle speed.

Check TPS when engine off. If .40-.46, then....
Check TPS and iac readings at hot idle.
If readings are outside of the recommended range, you'll have to adjust.
Remember to adjust iac first, then TPS. Adjusting iac affects TPS.

If it isn't the tps, it sounds like a vacuum leak. Those old hoses could be the culprits if they are the original from the 80's. Unless you changed them recently, they might be causing your issue.

 

[GNocide]

well i adjusted the set screw to have the car idle at 875
however my iac is still o- so vac leak or maybe bad iac?

 

[87-WE2]

well i adjusted the set screw to have the car idle at 875
however my iac is still o- so vac leak or maybe bad iac?

Great! Can you get your iacs to about 20 or so? If you are able to get them to come up, but they eventually fall to zero, you usually can attribute that to a vac leak. However, blms are usually high when you have a vac leak. I think you indicated a low blm reading at idle.

Keep in mind two things. One, that's not an idle screw. It adjusts the amount of air going in.
Two, When you fiddle with iac, the TPS will change for sure. Get TPS to .40 to .46 with key on engine off now.

Then go drive it and warm it up. Once hot, check both iac and tps at idle. If both are in range, then good. Once you've checked both at idle, kill the car, and with key on engine off, mat the gas pedal and verify your max TPS. If it is about 4.4 or higher, you should be done.

Don't get hung up on blms being a perfect 128. Plus or minus 10 is considered acceptable.

 

[earlbrown]

car idles high at 1400 rpm hot(fuel pressure is at 48 lbs- i thought that would be a cause of increased rpm- maybe not/)60lb injectors btw

2 IAC IS At -0 at idle hot= not 10-20 like the turbo tweak and other guidelines say it should be.

The reason the IAC is reading "0" is because you have the throttle blade open to far. The engine is getting too much air at idle and the IAC has closed completely off trying to bring the idle down.

Back off on the 'idle screw' (then reset the TPS to .42ish), turn the car off and then restart. When you get a reading of around 10 or so, make sure the TPS numbers are good on idle and WOT, then drive the car. Any fine tuning from that point will be easy.


the actual IAC number isn't as important as it's made out to be... that being said, it has to read something higher than 0. Personally I like to fine tune mine to read as low as possible while never hitting 0. That helps to avoid an off-idle cough ESP with bored out throttle bodies.

 

[we4Mateo]

The reason the IAC is reading "0" is because you have the throttle blade open to far. The engine is getting too much air at idle and the IAC has closed completely off trying to bring the idle down.

Back off on the 'idle screw' (then reset the TPS to .42ish), turn the car off and then restart. When you get a reading of around 10 or so, make sure the TPS numbers are good on idle and WOT, then drive the car. Any fine tuning from that point will be easy.


the actual IAC number isn't as important as it's made out to be... that being said, it has to read something higher than 0. Personally I like to fine tune mine to read as low as possible while never hitting 0. That helps to avoid an off-idle cough ESP with bored out throttle bodies.

Beat me to it! X2, turn the "idle" screw down until you get IAC counts, adjust TPS to be in range (.42 to .46 at idle and over 4.2 at WOT), restart and recheck and redo if needed.

FWIW, my iac counts seldom get down to 30 and are usually between 38 and 50. I can't open my "idle" screw any further to lower them any but my car runs great, so I leave it.

 

[earlbrown]

FWIW, my iac counts seldom get down to 30 and are usually between 38 and 50. I can't open my "idle" screw any further to lower them any but my car runs great, so I leave it.

You don't have an off idle 'hole' when you crack the throttle and go from almost only bypass air to buttloads from the TB?

 

[we4Mateo]

You don't have an off idle 'hole' when you crack the throttle and go from almost only bypass air to buttloads from the TB?

Nope. I can't say it NEVER stumbles, but it is very seldom and very small. I don't worry about getting across an intersection or anything from the "stumble" and I usually don't mess with minor tuning issues as long as they aren't a safety concern for myself or the car. I'd like to get my iac counts down, but I never investigated what it'd take to get the throttle blade open further and it's such a small detail in my overall tune that I'm inclined to leave well enough alone. Would a bigger TB help? I'm fast with my stocker so I've been inclined to leave that alone too. Any advice is appreciated.

 

[earlbrown]

Not really. A bigger throttle body doesn't really make a car faster, it makes the car feel faster and/or more powerful bottom end. With the same amount of pedal travel, the larger TB will dump more air than usual. It's the equivalent of stabbing the gas harder without actually doing it. That makes the car feel like it's making more power with the same amount of driver input. If you had a bigger TB, you'd probably have a bigger 'hole' to drive through before the car can adjust to the change in airflow.

The easiest way to bring the IAC's up would be to tweak the ear the minimum air bleed screw hits. It won't take much to let you get that screw back into resolution.

 

[GNocide]

what now?
adjusted the iac per turbodaves post.
also the tps right after,
scanmaster hot in park idle values: how far off am i?
o2 -636
af-05
l8-33
bat-12.4
int-128
bl-125
mph-0
clt-175
ats-110
tps-.44
iac-31
rpm-850
mal-(code 22 due to adjusting the tps)

 

[earlbrown]

Reset the code, verify your numbers and drive it around. When it's at actual operating temp see what the IAC reads in drive with and without the A/C on.

 

[we4Mateo]

what now?
adjusted the iac per turbodaves post.
also the tps right after,
scanmaster hot in park idle values: how far off am i?
o2 -636
af-05
l8-33
bat-12.4
int-128
bl-125
mph-0
clt-175
ats-110
tps-.44
iac-31
rpm-850
mal-(code 22 due to adjusting the tps)

Looks good but the bat volts seem a little low.