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-   -   2001 blazer 4wd Ls (https://blazerforum.com/forum/2nd-generation-s-series-1995-2005-tech-41/2001-blazer-4wd-ls-96912/)

GeorgeLG 05-19-2018 02:46 PM


Originally Posted by Davewho (Post 690490)
As far as drastic change in the fuel trim numbers I cleaned TB changed all vacuum lines as far as new # shrtft1 -0.8 LONGFT1 +11.7. shrtft1 +1.6. LONGFT2. +13.2 I changed to metric on scanner and got MAF 8.6 g/s rite at 890rpm

Please also restate your original fuel trims with +/- signs. Your new fuel trims are decent but not great so there may be some more improvement available. How many miles on this truck? They are way better than +/- 18 as before so something that you did may have already improved your situation.

A normal MAF on these engines seems to be 6.X at a normal Idle of 5XX. Your numbers are probably in the ballpark for your high idle.

Do your ECT temps on the scanner make sense? Ambient cold and 190ish warm. Also, watch the TPS data on the scanner with the truck off. Move the pedal back and forth a few times. Does the position data move the same every time and smoothly?

Do your O2 sensors make sense on the scanner. The readings should either be around 0.5V steady or should change up and down between around 0.3v and 0.8v.?

George

Davewho 05-19-2018 03:23 PM

Original stats SHRTFT1 0.0 LONGFT1 +18.8 SHRTFT2 +2.3 LONGFT2. +18.0 .There's 185,000 miles the ETC values I see are good just did TPS on scanner engine off it was smooth, as far as 02 sensors they just went as high as 0.938 while revving motor?? I also unplugged the IAC Then started the motor the idle went to little over 1200 I shut it off plugged it in the idle was back to normal range but other then cleaning TB real good changing some vacuum lines which half of them had holes in them I cleaned EGR valve replaced the PCV valve changed oil haven't done anything else and I really do appreciate you taking all this time and really helping me out and learning stuff as well so thank you sir

Davewho 05-19-2018 04:01 PM

Only dumb question is a un-asked question right well please explain blocking off vacuum line instead of pulling off and plugging it and where should I block it thank you

Davewho 05-19-2018 04:04 PM

I've also found bare wires somebody hacked the harness in a few places but I've looked all over and fixed all wires that were needing fixed me not finding all of them, could that cause hi idle and P0507 to come up???

GeorgeLG 05-19-2018 07:57 PM

Things I think that you have checked that are important:

Vacuum leaks
Leaks anywhere else in the airflow - gaskets, seals, etc.
IAC function/leaks
TPS sensor
Coolant sensor
Throttle body carbon

Things I don't think have been brought up:

EGR valve/gasket
Failed EVAP system
Quality of alternator/battery output - stability of voltage
Power steering pump pressure switch

Since your fuel trims are back to reasonable and you still have the problem I'm thinking voltage quality or the PS pressure switch.

George

Davewho 05-19-2018 08:43 PM

Ok I'll check that thank you brother for all the help

GeorgeLG 05-19-2018 09:02 PM

My pleasure, I hope we get you straightened out.

George
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Davewho 05-19-2018 09:26 PM

There's no doubt with your help it'll run better then it ever has

LannyL81 05-28-2018 09:10 AM

This is interesting, keep updating with what you find.

WalkGood 05-29-2018 01:50 AM


Originally Posted by Davewho (Post 690519)
There's no doubt with your help it'll run better then it ever has

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