EFI Check EngineLight/High Idle

[canzelc]

I am looking for some expert advice....

I recently completed a 5.0 conversion using the complete motor and EFI from a 91 Mustang and a RJM harness and A9L (NP435)

The engine runs great with the exception of a check engine light on and a racing idle. I am getting codes 10 33 81 82 84 and 85. The RJM instructions state that these are normal to be expected "soft codes" that should not turn the check engine light on (code 10 is not listed in my book). I have also read that the computer sets the idle and it is not adjustable.

Firing order and ignition timing (11 degrees before TDC) have all been double and triple checked.

I am having to turn the engine off at stop light because the idle races so high. If anybody can point me in the right direction I would really appreciate it!

 

[markperry]

You may have this website, but if you don't here you go it's helpful!

http://web.archive.org/web/20110414061839/http://fordfuelinjection.com/?p=44

 

[jw0747]

Good write-up on this link about correcting idle problems. Computer probably needs to be reset especially if it hasn't been connected to a battery for a lengthy period of time. Such as during the time it took to do the conversion. Instructions on procedure are on page 3. Steps 1-9 under "How to do it."

http://www.muscularmustangs.com/iac.php

 

[ransil]

Reset base Idle first
Is you IAC mounted connector down, mine would high idle with it up.
Bad/Sticking IAC
Vacuum leak

 

[canzelc]

Thanks for the links, they seem to be very helpful. I have set aside some time next week end to clean out the IAC and reset the base idle. I will let you guys know how it goes.

Has anybody used the RJM harness? I am wondering if there is anyway to clear the codes that the instructions say should not turn on the check engine light or any trick to turn the light off.

Thanks again for all your help!

 

[Broncobowsher]

Backwards IAC is a common one. They have a flow direction. Run them backwards and they often can't correctly control the flow. The bolt pattern is symmetrical so it is easy to do.

 

[canzelc]

Ok.....I have been messing around with thing for the last few months and I haven't made any head way. I have replaced the IAC and reset the base idle and I am still having the same problem.

At this piont I would like some recomendations on a shop that I can take it to locally that has experience working with these types of efi conversions. I live RWC which is half between SF and SJ.

Anybody know of a good shop?

 

[Sporto]

I know that you're ready to take it someone to look at, but these symptoms really sound like a vacuum leak somewhere. Think about it for a second...The IAC is supposed to regulate all air entering the engine at idle, so if you have already set the TPS sensor and throttle plate then you should have a low idle because the IAC (and it's variable sized opening) is managing the air intake, and in turn the idle speed. However you're idling high at all times, the only logical condition that would make this happen is if more air is getting into the engine somewhere and the computer is compensating for it making your idle high.

If you're certain that it is not a vacuum leak then take a look at code 33.

Code 33 - Insufficient EGR flow detected.

This could be an indication that the resistor in the RJM harness is not connected properly, and it is sending a false reading to the computer. When I delete an EGR and wire in the resistors, I get the soft codes you indicated, but I don't get a 33 nor the CEL illuminating. Therefore, there may be an issue in your harness regarding the resistors installed to allow the computer to think the EGR is still there.

I dunno, these are some of my thoughts when reading your posts.

Good luck with it!

Rich

 

[Hozr]

There are a bunch of Factory Five cobra guys that have tons of experience with the mustang swap down in the Bay Area. Check on CAFords and FFCobra forums as well

 

[canzelc]

I know that you're ready to take it someone to look at, but these symptoms really sound like a vacuum leak somewhere. Think about it for a second...The IAC is supposed to regulate all air entering the engine at idle, so if you have already set the TPS sensor and throttle plate then you should have a low idle because the IAC (and it's variable sized opening) is managing the air intake, and in turn the idle speed. However you're idling high at all times, the only logical condition that would make this happen is if more air is getting into the engine somewhere and the computer is compensating for it making your idle high.

If you're certain that it is not a vacuum leak then take a look at code 33.

Code 33 - Insufficient EGR flow detected.

This could be an indication that the resistor in the RJM harness is not connected properly, and it is sending a false reading to the computer. When I delete an EGR and wire in the resistors, I get the soft codes you indicated, but I don't get a 33 nor the CEL illuminating. Therefore, there may be an issue in your harness regarding the resistors installed to allow the computer to think the EGR is still there.

I dunno, these are some of my thoughts when reading your posts.

Good luck with it!

Rich

......Ok I will check for a vacuum leak, what is the easiest way to check?

Also I would like to check the resistor for the egr delete in the rjm harness, does anybody have a wiring diagram for the harness or know where it is located? What is the proceedure to check it once I locate it?

I did a Google search and could not find any wiring diagrams.

 

[Viperwolf1]

......Ok I will check for a vacuum leak, what is the easiest way to check?

Also I would like to check the resistor for the egr delete in the rjm harness, does anybody have a wiring diagram for the harness or know where it is located? What is the proceedure to check it once I locate it?

I did a Google search and could not find any wiring diagrams.

Code 33 is normal with the resistors in place. It will not cause a CEL to light. You have another problem, possibly in the ECM itself.

 

[canzelc]

Is there a way to check the ECM?

 

[Sporto]

......Ok I will check for a vacuum leak, what is the easiest way to check?

A vacuum gauge is a good place to start.

http://www.carid.com/actron/vacuum-..._fGT2jhiHZqIMGC2p8w5_u9lerPt0MN9fwaAvAg8P8HAQ


These gauges can speak volumes to you about what is going on in your engine. A tight motor, properly timed and with no leaks should have a steady needle around 17-21lbs. Any other type of activity is indicative of an engine problem. A leak would result in a much lower vacuum reading.

http://www.mtfca.com/discus/messages/29/13704.gif

Regarding the Code 33...I've never seen it appear in my stuff, but I would go with what ViperWolf says. He is much more skilled in the ways of EFI and computers than I am, so maybe find someone who could lend you a similar computer and swap it out and see what it does.

Good luck!

Rich

 

[Labbster]

I just had a high idle problem a few days ago. I checked and checked for a vacuum leak and could not find one. I took off the IAC and there was a lot of carbon build up. I took a pick and moved it up and down to unfreeze it. Put it back on and the idle came down a ton. Took it completely off and put on a new one. Idle high for about 10 seconds...which felt like 10 minutes, and then....idle slowed and all is good...

 

[canzelc]

So I got around to checking the TPS voltage. I have read that it is supposed to be set at .99-.98 volts. Mine is reading 1.48v.

Do to hood clearance issues I used bugle head machine screws to secure the TPS sensor to the throttle body that are not allowing me to set the voltage properly. I will have to change fasters and field engineer the TPS sensor so that I can set the voltage properly.

What effect does the TPS voltage being that far off have on the idle?

 

[Viperwolf1]

So I got around to checking the TPS voltage. I have read that it is supposed to be set at .99-.98 volts. Mine is reading 1.48v.

Do to hood clearance issues I used bugle head machine screws to secure the TPS sensor to the throttle body that are not allowing me to set the voltage properly. I will have to change fasters and field engineer the TPS sensor so that I can set the voltage properly.

What effect does the TPS voltage being that far off have on the idle?

I'm sure it would have a big effect at idle. Surprised you don't get a TPS code though. Anything above 1.2V or below 0.49V should set the code.

 

[canzelc]

I have changed the fasteners and currently the TPS voltage is 1.068v. To adjust further I would need to make the holes on the TPS larger. I have not had a chance to drive it yet to find out if the idle will stabilize.

Is 1.068v "close enough" or should I make the holes bigger to get it to .99-.98v?

 

[904Bronco]

I have changed the fasteners and currently the TPS voltage is 1.068v. To adjust further I would need to make the holes on the TPS larger. I have not had a chance to drive it yet to find out if the idle will stabilize.

Is 1.068v "close enough" or should I make the holes bigger to get it to .99-.98v?

Yes you should slightly enlarge the holes with a small file in the direction that you need to turn the sensor to get the desired voltage reading. Left you the same message on Norcal Broncos...

 

[Viperwolf1]

I have changed the fasteners and currently the TPS voltage is 1.068v. To adjust further I would need to make the holes on the TPS larger. I have not had a chance to drive it yet to find out if the idle will stabilize.

Is 1.068v "close enough" or should I make the holes bigger to get it to .99-.98v?

It is good. It needs to be between 0.49V and 1.2V.

 

[canzelc]

I have ironed out the hood clearance issues and set the TPS voltage with the engine off (.99v). Should the voltage be checked with the engine running or not or does it matter?

I have not had a chance to drive it yet due to the weather. I got a vacuum guage and if I get a chance tomorrow I will check to see if I have a leak. hopefully it does not rain all day tomorrow so I can take it for a test drive.