The Pepsi Saga: Injector Indulgance

[AL]

Yes 18 inches of vacuum at idle... and the green 3 wire plug goes to the MAP sensor but I am not sure what the red and blue plug is... Can you post a pic?

[RobertISaar]

91. I thought the Map sensor was the blue and red plug with the larger vacuum line attached

 

red and blue plug sounds like the purge solenoid for the carbon cannister. MAP sensor has 3 wires, purge solenoid has 2. the purge solenoid also has two lines attached to it, compared to the 1 the MAP sensor has.

 

40kpa abs is like 40% of atmospheric, which is like around 30" Hg. so a reading of 18" Hg (gage) should be the same.

 

sounds about right.

[mra32]

so it was at 18 In Hg (also had kpa on it, lol) then it started running crappy and went back and forth between 15 and 16. I think this was due to the lower rpm

[mra32]

hmmm map sensor broke off like a year and a half ago and has been dangling by that rigid plastic vacuum line since. but my last test seems to suggest that i dont have a vacuum leak. Maybe the sensor itself is bad.

[mra32]

also kinda looking at egr...but it doesnt seem like it would cause these kinds of issues at the times it does

[RobertISaar]

EGR should not be commanded at idle... though it does have a coolant temperature and time since started vs coolant temp requirement.

[mra32]

so if the egr was infact causing my issue then it would suggest the ecm is bad. Unlikely that it would fail in that way. I'm running out of electrical things to test and going back to my mechanical issue hypothesis.

[RobertISaar]

if the EGR was causing the issue, then yes, either the ECM or MEMCAL is about to shit the bed one last time.

 

pull the plug on the EGR and see if that fixes the idle. if so, you're guaranteed the ECM or MEMCAL is junked. if not, look elsewhere. mechanical doesn't seem to make sense if it happens with this kind of consistency, unless it's effecting a sensor that the ECM depends on.

[mra32]

I unplugged da egr and drove around for a while and i dont think it did much. It didnt even set off a code. Whats the danger if any with running without the EGR?

[RobertISaar]

when the ECM commands the EGR, it does two things: leans out the amount of fuel injected to compensate for the addition of inert substances in the combustion chambers, and adds spark advance, to compensate for the fact that inert substances will not burn in chamber, so it gives it more time to build up pressure to maximize power.

 

now... fueling eventually gets fixed thanks to the O2, but if it knocks because of the added advance, it will continue to do so, with the knock sensor sending it's signal to the ECM, the ECM retarding timing, then adding it back in, knock happens again, and the cycle repeats continuously. EGR also helps prevent burnt valves(ironically enough) due to lowering peak combustion temps due to the inert substances taking up volume and lowering temps.

 

take it for what it's worth...

 

you'll likely only set of the EGR code by getting up to ~60MPH or higher, then completely letting off the throttle(a downshift helps as well), since that's the only time the ECM tests for EGR functionality.

[WhatTheFehl]

you'll likely only set of the EGR code by getting up to ~60MPH or higher, then completely letting off the throttle(a downshift helps as well), since that's the only time the ECM tests for EGR functionality.

 

I got the EGR code thrown regularly at 45 mph.

[RobertISaar]

3100 PCMs have much more strict conditions as well.

[mra32]

red and blue plug sounds like the purge solenoid for the carbon cannister. MAP sensor has 3 wires, purge solenoid has 2. the purge solenoid also has two lines attached to it, compared to the 1 the MAP sensor has.

 

 

 

sounds about right.

 

Robert, thanks for the diagram. I noticed it didnt have the attachment on the intake manifold for the brake booster. Thats a vacuum line, right? Should there be any more vacuum lines to worry about

[RobertISaar]

well, that was emissions lines, which should have covered most of them, and actually shows the HVAC line too.i can't think of any more that would be present, except maybe a vacuum resivoir.

[mra32]

drove w/o the oxygen sensor hooked up and it worked pretty dang well. cleared up whatever issue i was worried about. I should have listened to you guys like 4 years ago when I got the bosch oxygen sensor and you guys didnt recommend it.

 

Now, can I immediately consider my issue solved and purchase and install a new oxygen sensor or does this just narrow my path in fixing this?

[RobertISaar]

sounds like you found your issue... new O2 and call it fixed....

[mra32]

sweet! denso O2 sensors for 14.57 shipped from rockauto!

[mra32]

so this is like the longest "my O2 sensor is fucked" thread ever. Oh well. I never gave up and worked on it when I could. So what are the effects of driving without the O2 sensor hooked up. My car was alot smoother.

[RobertISaar]

obviously no correction to fueling, so you could be super rich or super lean and the ECM wouldn't know it. but as long as it runs somewhat correctly, i would disregard until a new O2 comes around.

[tornado_735]

Sweet

[mra32]

still does this kinda. Seems to be heat affected. On rather hot days its worse. Could this be coil/wire related?

[RobertISaar]

it's certainly possible.

[mra32]

would someone want to provide me with known good coils/wires that fit my car??

 

how about the ICM, is its operation likely to be affected by heat?

[RobertISaar]

ICMs can definitely be effected(affected?) by heat soak.

[tornado_735]

Dumb question, but do L82 coils fit an LH0? If so, i have coils I'd let you have for on the cheap.

Edited September 21, 2010 by tornado_735