1G odd idle and vacuum

[enriquez2000]

If my car is in park or neutral I have a good solid idle set through ecm link to stay at 900rpm and my vaccumm is at -18. Now when I put the car in gear ecm link will keep me idling at 900 but you can hear and feel the motor working more and the vaccuum jumps up to -12. Occasionally it feels more rough at a stop light but goes away as soon as i put it in neutral. Keep in mind this is an awd auto.

The only thing I could think of is something going funky in the tranny but it shifts through gears just fine while driving. Basically just looking for ideas of what to look at.

 

[turtlebain]

Hmmm check the ISC / IACV, biss adjustment , obviously you've double checked all vacuum lines.... Are you recirculating the BOV?

 

[enriquez2000]

Hmmm check the ISC / IACV, biss adjustment , obviously you've double checked all vacuum lines.... Are you recirculating the BOV?

Iacv is deleted. Isc and biss read right on link..

 

[enriquez2000]

another thing i noticed.. when i turn the ac on my cacuum can go as high as -10... it seems like anytime the car is under a load I have the issue. Also this throttle body is a new rebuild but had same problem on the other throttle body as well.

 

[turtlebain]

OK, I actually thought you meant you were having issues coming to a stop, that's why I mentioned BOV recirculation.

I'm not so familiar with auto trans. Maybe someone else can chime in that knows a little more how they can affect idle. It sounds like the transmission pump is turning on and creating this situation.

Just FYI the IACV and ISC is the same thing. You wouldn't want to delete it, but it doesn't sound like you did.

Is it something that just started? or was it always that way?

 

[portum89]

This happens to an old car we had, a ford escort. As soon as you went in Drive it would struggle a little bit pulling more vaccum, so we would put it in Neutral. I could only assume that it is a vacuum leak? I would perhaps up the idle to 1000 if it keeps doing it to help with the surges if any.

 

[enriquez2000]

OK, I actually thought you meant you were having issues coming to a stop, that's why I mentioned BOV recirculation.

I'm not so familiar with auto trans. Maybe someone else can chime in that knows a little more how they can affect idle. It sounds like the transmission pump is turning on and creating this situation.

Just FYI the IACV and ISC is the same thing. You wouldn't want to delete it, but it doesn't sound like you did.

Is it something that just started? or was it always that way?

i deleted the fitv(coolant part). I dont know anything about auto trans but i have to assume its related if it idles fine in neutral but goes to -12 under load in drive.

I wonder if there is a trans vacuum line im missing. I boost leaked test the heck out of this car which is why the TB was rebuilt. I now hold 26psi no problem.

 

[95mitsubGSX]

I was always under the impression that anytime the car went under load you would lose vacuum based on the motor working harder to try and keep the idle up. And unless the 1g transmission is significantly different then a 2g there are no vacuum lines to it.

 

[enriquez2000]

Shouldnt be a

I was always under the impression that anytime the car went under load you would lose vacuum based on the motor working harder to try and keep the idle up.

should lose some... but i wouldnt think this much

 

[95mitsubGSX]

I will check how much I lose when I get home.

 

[95mitsubGSX]

I loose about 5 psi of vacuum from park or neutral to drive. No ac on the car but would figure a few more if the ac is running.

 

[portum89]

How many miles you got? It could also be engine wear at this point. Are you on stock cams? Try 1k rpms and it may make the hesitation a little less, but not fix it perhaps.

 

[enriquez2000]

Yes i have stock cams and i know i have valve seal leaks Because if i let it warmup for 10min i blow smoke until it clears out but none if i start and drive. Im at almost 150k.

 

[95mitsubGSX]

I am at like 5 miles.

 

[95mitsubGSX]

Probably about an hour of idle time and 5 miles on the motor. Still running stock cams as well.

 

[enriquez2000]

Probably about an hour of idle time and 5 miles on the motor. Still running stock cams as well.

well if yours is dropping 5 then im pretty in line with you.. so at 150k miles i guess I wont worry too much