Running Rich, even after warm start up.

Sik89supra

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Jan 13, 2009
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Delta PA
It just started doing this, its running real rich, when i start it up, every time i start it up even when i start it up after running it to operating temps. and it takes like 20 mins for it to go back to a good AFR, i thought it might be a bad cold start injector time switch, so i unplugged it and no difference, anyone have this problem before.
 

paradox616

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Sep 12, 2008
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what kind of AFR's are you seeing?
How are you measuring them? narrorband/wideband?
Are these on idle or under load/boost?

[removed to make jdub happy]
 
Last edited:

jdub

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paradox616;1402358 said:
Just a few thoughts
could have a faulty ECU temp sensor, the gauge sensor is NOT the same as the ecu sensor.
the ecu will have a coolant temp vs AFR table in it. if the sensor is reading the car as colder than it really is then it will inject more fuel


Ummmm...did you make this up or are you smoking something good again?

A failed (or unplugged) ECU sensor will cause the ECU to go into one of it's fail-safe modes. The ECU will substitute a temp of 80 deg C for all calculations. That temp is the lower threshold for the normal ops temp range (80-100 dec C). If anything, the car will be more difficult to start (start-up enrichment at min) and will run lean during warm-up (warm-up enrichment is disabled).

The ECU does not use a temp table to determine injector duration...it's:

basic duration + injector corrections + voltage correction = final signal duration

Coolant tmp is one of several inputs to the injector correction coefficients.

Do us a favor Paradox - STFU unless you are 100% sure of what you're talking about in the Tech sections. This was so off base it isn't funny.
 

paradox616

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jdub;1402374 said:
Ummmm...did you make this up or are you smoking something good again?

A failed (or unplugged) ECU sensor will cause the ECU to go into one of it's fail-safe modes. The ECU will substitute a temp of 80 deg C for all calculations. That temp is the lower threshold for the normal ops temp range (80-100 dec C). If anything, the car will be more difficult to start (start-up enrichment at min) and will run lean during warm-up (warm-up enrichment is disabled).

The ECU does not use a temp table to determine injector duration...it's:

basic duration + injector corrections + voltage correction = final signal duration

Coolant tmp is one of several inputs to the injector correction coefficients.

Do us a favor Paradox - STFU unless you are 100% sure of what you're talking about in the Tech sections. This was so off base it isn't funny.

fine what ever. i bet you amuse yourself.
 

jdub

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Sik89supra;1401915 said:
It just started doing this, its running real rich, when i start it up, every time i start it up even when i start it up after running it to operating temps. and it takes like 20 mins for it to go back to a good AFR, i thought it might be a bad cold start injector time switch, so i unplugged it and no difference, anyone have this problem before.

There's no way the CSI can be responsible unless it's leaking or stuck open...unplugging it will not determine if it is or not. The CSI is only active when the starter is engaged.

Have you checked ECU codes?
 

jdub

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paradox616;1402383 said:
i never said it could have been unplugged, fine but no need to be a rude cunt. *waits for ban*

I'm not going to ban you unless you keep the abusive language up. I was not being rude, I was being blunt...I have to correct crap like this all the time and the number of PMs I get because of misinfo like this fills my inbox. Something you don't have to deal with, but I do.

I will agree that if a ECU temp sensor is reading cold (<80 deg C) the ECU will stay in warm-up enrichment. It will have to be tested per the TSRM to determine that. The rest of what you said is 100&#37; BS.

Consider this a warning...any more posts that are not accurate in the Tech section will result in an infraction.

Nice ninja edit:

paradox616;1402383 said:
fine what ever. i bet you amuse yourself.

Just so you know, the mods can see all edits done to a post. I didn't this time because I responded before you changed it.
And, no I'm not amused...do not push me.
 

wiseco7mgt

dirty mechanic
Aug 12, 2007
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queensland
Mine runs a little on the rich side (13.9-14.1) as well, but no codes and the ecu is happy at 2.5v. ::shrug:: not urgent but down the track may need Jdubs technical advice.
 

Sik89supra

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Jan 13, 2009
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No codes, it ildes around 12.5 and only gets richer as i drive untill about 20 mins or so later then it goes back to 14.6, im using a LC-1 Wideband
 

jdub

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Do you have a coolant T-stat installed and what temp is it?

What is your coolant temp gauge doing during the 20 mins?
 

Sik89supra

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yes it has the t-stat in. i got it from toyota, and the gauge reads normally, and raise's to normal temps, like it should, the amount of time it takes to get to operating temps hasnt been affected.
 

jdub

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So, 5 min or so for the gauge to read normal ops temp?

Next time the car is full cold, unplug the ECU coolant temp sensor and start...might take a little longer to start. Note what the AFR is as the temp guage gets to ops temp.
 

Sik89supra

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ok unplugged to Coolnt temp sensor, and it made it run even richer(11.0), i only let it idle for a few mins, cuz it was running so rich. Thanks For the help jdub
 

jdub

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Ok...it should not have done that! Pull the EFI fuse for a min, replace, and try it again.
 

jdub

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Leave the ECU temp sensor unplugged and drive till it warms up. See if there is any difference. BTW - this should set a code 22. After all this you will have to clear it.
 

Sik89supra

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No difference, i plugged the CSI Just to see if maybe the injector was stuck open or something, and besides it being harder to start when cold, the AFR was 12.0-12.5 But it doesnt take as long for it to get back to normal AFR, it acts like everything is working normally, but shouldnt the AFR be around 14.6 when i start it up with the CSI out?
 

jdub

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Sik89supra;1403276 said:
No difference, i plugged the CSI Just to see if maybe the injector was stuck open or something, and besides it being harder to start when cold, the AFR was 12.0-12.5 But it doesnt take as long for it to get back to normal AFR, it acts like everything is working normally, but shouldnt the AFR be around 14.6 when i start it up with the CSI out?

Was the ECU temp sensor still unplugged when it didn't take as long to get a normal AFR?

If you read my post on the previous page, the CSI is only active when the starter is engaged. Unplugging it will make the motor harder to start, but will have no effect on AFR once the motor is running if it is functioning normally. The CSI has to be mechanically stuck for it to cause a rich condition.

A stoich (14.7) AFR will not occur until the engine is warmed up and the ECU comes out of warm-up enrichment.

I'm a bit confused on exactly what you did since we were working on the ECU temp sensor. Need to do one step at a time or better explain what you did if I'm going to be able to help you.
 

Sik89supra

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Sorry about that, no the temp sensor was plugged back in, i tried leaving it unplugged and running it but still the same problem(running rich and and taking a long time to reach normal AFR which for my car was right around 14.6. So i unhooked the fuel line from the fuel rail to the CSI to test if maybe the CSI was stuck open for any reason and dumping in fuel all the time. With the Fuel supply for the CSI off, once the engine was started it would only take 1 min or 2 for it to go to 14.6, instead of the 20 mins or so it would take it to get to 14.6 when i had the fuel supply line hooked up for the CSI.
 

jdub

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Outstanding! All this I had you do with the ECU temp sensor was to eliminate it as a problem...what you've told me has done that. Make sure you clear the ECU codes.

Next on the list was to:
- Check the TSRM FP range (the FPR)
- Check that the FPR was not open to atmosphere (bad vac line or VSV), thus increasing FP off boost
- Disconnect the CSI fuel supply

Any of the above can cause this problem in no particular order...you just jumped straight to the CSI (which is fine). What the motor is doing now with the CSI fuel supply disconnected is normal, but as you discovered it will be more difficult to start. The hard start will get worse as it gets colder outside. You can either have the CSI cleaned/tested or you can buy a new one.

Looks like to me the problem is solved ;)