idle speed adjustment

[FlaD90]

I just performed an oil change & cleaned the K&N air filter today. Needless to say the air cleaner was very very dirty, I was going to clean the air -intake but could not find my cleaner spray and just bolted everything back together again.

Afterwards I switched the battery kill switch to off for a few minutes and back on, it seems to be idling a bit higher than before & is stting at 1,000 RPM right now....is this what the default idle speed should be???...maybe I have way too much noise comming thru the 5 spd console cover which is broken right now and It could just be all in my head.


Any thoughts on this?

[Hans]

You have absolutely nothing wrong, most likely. The computer just needs to re-learn the idle speed profile, which comes with just driving the truck. The more you drive around in stoplight territory, the faster the idle gets back to where it should be.

[FlaD90]

Much thanks Hans.....driving the D90 is one of my favorite things to do.

[Cmikefly]

Ok. I guess its time to stop working on lift kits and bumpers and sort out the last of the mechanical problems with my D90. Any help is appreciated (and much needed)



Here is what I have



Idle speed is all over the place. Sometimes when I start the truck it runs perfect. Settles in at around 700rpm and remains there regardless of A/C or gear selection (97 Auto). However the majority of the time when I start the RPMs will rise to around 2000, drop to around 1500 momentarily, then increase back to 2000. When I select reverse or drive the RPMs will drop to around 1000. When I select Park or Neutral prior to shutdown the RPMs will slowly rise to around 1200 for a few seconds then shoot back up to 2000. I have replaced the TPI and stepper motor for lack of a better idea. When the truck is idleing correctly I am able to adjust the speed via the allen key set screw in the intake.



Additionally I am unable to get the OBDII reader to work. I ordered a generic reader from Summit Racing but it will not communicate, (I works fine on a friend’s 2000 RR). I took the truck down to the local LR dealer and they were also unable to connect, and insisted that the engine/gearbox setup was not original because they have never seen it before.



any ideas please?

[ECR]

Additionally I am unable to get the OBDII reader to work. I ordered a generic reader from Summit Racing but it will not communicate, (I works fine on a friend’s 2000 RR). I took the truck down to the local LR dealer and they were also unable to connect, and insisted that the engine/gearbox setup was not original because they have never seen it before.



any ideas please?

Do you have a stock radio or an after-market unit?

[FlaD90]

my idle speed for the most part is sitting at 1k RPM, but I dont have AC also. My 94 has ODBC-2 so I cant compare.

startup at 1500 then drop to 1k.

[Cmikefly]

I have Kenwood DVD/GPS unit. Could that be part of the problem?



Thought you may enjoy the attached photo………….

[ECR]

I have Kenwood DVD/GPS unit. Could that be part of the problem?



Thought you may enjoy the attached photo………….


Yup.
The reason you can not communicate with the ECU (computer) is your stereo installers know nothing about Defenders. In the storage locker under the RH front seat is/was a factory amp for the speakers. In the wiring there for the speakers there are additional grounds. What the stereo morons do is cut the wires and join the speaker wires together (or eliminate them if they ran better quality speaker wires to your speakers). The issue is that there are a few black ground wires there that relate to the grounds of the EFI ECUs diagnostic port. You need to join them back together and then the ECU will talk the code reader at the dealer.
As a test you can hook up a computer/code reader, turn the key on. Then turn the key to the ACCESSORY position. At that point you'll have about 30-45 seconds that you can access the ECU. (as when it times out and stores codes via a different ground and you will have access). Fix the botched stereo install and you'll get full access to the ECU again.
We see it all the time. Even seen a lot of people buy new ECUs to "fix" the problem.

Once you get into the ECU you can then start working on the cause of your idle issues correctly.

[Cmikefly]

Thank you for the information, I would have never figured that one out…. The stereo installer (me) cut the entire bundle of wires and removed them. I sealed the bundle FWD of the cut and left it in the split loom near the T-case. Will open it up tomorrow and see what I can find.



Thanks again.

[rover4x4]

Yup.
The reason you can not communicate with the ECU (computer) is your stereo installers know nothing about Defenders. In the storage locker under the RH front seat is/was a factory amp for the speakers. In the wiring there for the speakers there are additional grounds. What the stereo morons do is cut the wires and join the speaker wires together (or eliminate them if they ran better quality speaker wires to your speakers). The issue is that there are a few black ground wires there that relate to the grounds of the EFI ECUs diagnostic port. You need to join them back together and then the ECU will talk the code reader at the dealer.
As a test you can hook up a computer/code reader, turn the key on. Then turn the key to the ACCESSORY position. At that point you'll have about 30-45 seconds that you can access the ECU. (as when it times out and stores codes via a different ground and you will have access). Fix the botched stereo install and you'll get full access to the ECU again.
We see it all the time. Even seen a lot of people buy new ECUs to "fix" the problem.

Once you get into the ECU you can then start working on the cause of your idle issues correctly.


I hate for you to tell all of your secrets but how does one bypass this amp without mucking up the grounds? Is this only an issue for the OBDII trucks?

[ECR]

I hate for you to tell all of your secrets but how does one bypass this amp without mucking up the grounds? Is this only an issue for the OBDII trucks?

Just connect the black wires so it is like they were flowing through the amp., and do everything else like you normally would.
The issue only comes up when people connect the speaker wires but leave the black wires hanging, or when they cut all those wires away.

Yes, this is only for GEMS (1997 90s).

Can't tell you how long it took me to find that the first time... lots of unbillable hours on that customers car, but in the end he was happy we were able to solve it. Benefits of working on Defenders for 15 years.
Sadly he had already bought another ECU because the dealer told him he had to.

[Cmikefly]

OK I was able to open the wiring loom and find the ground wires that went through the Amplifier. Easy fix once armed with the correct information. Thanks again ECR.



The scanner and live data functions are working fine now with the following codes coming up:



P1317

P0460

P3999



While looking at the live data I noticed that the “Air Status” as OFF even when the A/C is on?



Now that I am able to look at codes does anyone have any idea on how to go about identifying and rectifying the idle speed problems?



Thanks in advance.