EEC-V Question

[tbrtuning]

Does MAF transfer effect idle control on the EEC-V? I have a car to tune that I don't want to pay to license if it has a mechanical problem. With the MAF unplugged the car idles fine (not good but it idles at a normal RPM)... With the MAF plugged in the idle immediately shoots up to the neutral RPM limit of around 4,000 RPM.

Would the MAF calibration in the tune being way off cause that on these cars or is it just bypassing an idle air control method under failed MAF conditions? It still does it with IAC unplugged is a strange thing also.

[jchambers]

The airflow measured by the MAF is still controlling the fueling under the idle control strategies. You've got something amiss that needs more diagnosis.

[tbrtuning]

Thanks for the reply. So you think something mechanical needs fixed and just the tune being off would not cause this? That's what I was thinking until I unplugged the MAF and it didn't do it. I'm new to the EEC-V though so was hoping to get an opinion from someone more experienced like you.

[realspeeddan]

It sounds like you have a throttle stop set way too high, stuck open or an IAC jammed open to let way too much air in.

One guess would be that with the MAF unplugged the Failed MAF table isn't giving it enough fuel to let it rev the way it wants to, but with the maf working then the appropriate amount of fuel is being added to match the airflow, so then engine actually runs well enough to free-rev as high as it can because the throttle is stuck open.

[tbrtuning]

Thanks. I was wondering about that because it does stumble running off failed MAF so definitely isn't making much power to rev that way.

[tbrtuning]

Well new IAC didn't fix it. Throttle is closed all the way too.

[jchambers]

I'd say that you have an unmetered air leak, except as rsdan says when the MAF is plugged in its metering the air and adding the fuel accordingly. Think we'd all need more detail to try and help. What model car? Intake & TB details, datalog, tune file, etc. Look at the TB gasket. I have seen where the gasket isn't correct and lets air bypass the IAC, causing a huge metered leak and high idle condition.

[tbrtuning]

Thanks. Going to check that next. It seems like a lot of air getting to the engine is the only way this could occur. I not tuning this with HP Tuners is why I didn't post a log or anything. Everything I could think to check looks fine in the log... MAF seems to respond to airflow changes, TPS reads normal, engine speed and other normal parameters read as expected.

[tbrtuning]

Well I just asked the owner and got a response about the guy he got the upper intake from probably doing some kind of modification to accept a single blade that messed up the IAC? I'm not familiar with the common modifications on these cars yet. Does that seem reasonable?

[jchambers]

Completely possible. I'd inspect the IAC path through the intake/TB.