My 1996 D1 with (173K mi) idles high (900 - 1100 rpm) about 50% of the time. Any suggestions as to how I would go about troubleshooting this?
High Idle on 1996 D1
- Thread starter syugg
- Start date
I'd start with making sure there are no vacuum leaks, and the IAC solenoid (a.k.a. stepper motor) is clean and working.
Replaced the stepper motor/idle air control valve after cleaning the original one and it didn't help. Cleaned the mass air flow sensor and that didn't help. Swapped the mass air flow with another and that didn't help. PCV hoses seems fine. The truck still idles high every so often. What else do I need to do to troubleshoot this issue?
Would leaks between the plenum chamber and ram housing or the ram housing and intake manifold cause my idling issues? When these parts were removed and replaced during my head gasket job, I may not have prepped the surfaces properly. Any thoughts?
I had high idle issues but mine was the ECU and this doesn't sound like your problem if it only does it sometimes..
If you love your Discovery or any vehicle and have a little money to throw around get a scan gauge. It will tell you your TP and if your trucks running in open or closed loop and MUCH more.
If you love your Discovery or any vehicle and have a little money to throw around get a scan gauge. It will tell you your TP and if your trucks running in open or closed loop and MUCH more.
Ed Cheung said:
The plug to the maf appears fine. When I disconnect the plug while it's idling high, it idles normal. If I plug it back in, the idle shoots back up to 1100-1500 rpm.
Is there a way to test the maf?
Eh kinda..
You will get a check engine light..
If you drive without it pluged in, you will notice a hesitation when accelerating from a stop. Definatly noticeable. Took almost 3 hours of driveing before I found out my maf was unplugged..
You will get a check engine light..
If you drive without it pluged in, you will notice a hesitation when accelerating from a stop. Definatly noticeable. Took almost 3 hours of driveing before I found out my maf was unplugged..
Over the phone one rover shop quoted 1 hour of labor to reflash the ecu. Another rover specialist said that a 96 disco ecu can't be flashed but would charge 1-1.5 hrs to diagnose. When initially describing the symptoms to both shops they had a reaction like they haven't heard about reseting the adaptive values.
Is an hour of labor time reasonable ($135/hr) to reset the adaptive values? It seems excessive just to plug in to the ecu and punch a few keys on the computer.
Is an hour of labor time reasonable ($135/hr) to reset the adaptive values? It seems excessive just to plug in to the ecu and punch a few keys on the computer.
syugg said:
Call them back and tell them they need to shut the doors because they do not know shit.
ptschram
Well-known member
I charge $95/hour for computer diagnostics, but the secret is things like this can be done for a Case of Sierra Nevada or Ranger IPA. OTOH, if you send me an ECU and I open it up, clean the boards, reset the values and put it in security learn mode, that's gonna cost you $200.
If this happened as a result of major engine work, the ECU has to have the adaptive values reset as you have changed things and the ECU doesn't know it yet. resetting the adaptive values returns you to factory settings and allows the ECU to learn the new engine conditions.
If it's intermittent, I'd be looking to the TPS. Vacuum leaks tend to not be intermittent under most conditions.
Otherwise, Chapman's on the right track as much as I hate to admit it.
If this happened as a result of major engine work, the ECU has to have the adaptive values reset as you have changed things and the ECU doesn't know it yet. resetting the adaptive values returns you to factory settings and allows the ECU to learn the new engine conditions.
If it's intermittent, I'd be looking to the TPS. Vacuum leaks tend to not be intermittent under most conditions.
Otherwise, Chapman's on the right track as much as I hate to admit it.
Well it turned out that bringing my truck into my rover mechanic to reset the adaptive values did the trick. Truck now idles normal and smooth throughout the RPM range.
I'm guessing that after I did a head gasket replacement and a few other items may have changed the parameters enough that the adaptive values needed to be reset. It was just strange since the erratic/high idle didn't occur until a month or two after I did the head gasket work.
Thanks to all here for your help!!!
I'm guessing that after I did a head gasket replacement and a few other items may have changed the parameters enough that the adaptive values needed to be reset. It was just strange since the erratic/high idle didn't occur until a month or two after I did the head gasket work.
Thanks to all here for your help!!!
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syugg said:
Just wanted to let you know, I paid 136$ for mine and was great for about a month. Then returned to normal. Im very pissed and will never "just reset the ecu." SOMETHING caused it. And if yours happened RIGHT after the headgasket change then I guess its fine.
Timmy!!!!!!! said:
NONE.
I have experimented with this alot. I bought a scangauge and shortly after saw my TPS started jumping. I replaced it but it seems the computer has "learned" the old TPS, im going to see If I can drive my truck to RElearn the correct settings.
HOWEVER I don't believe this is the issue, as I replaced my IACV with my old one and the idle is different. With the first one it would idle high and stay there, with this one, it seems to idle high at start up and then come down as if nothing ever happened, but then comes back up randomly. Sounds like its a bad IACV, but whats the chances of 2 BAD IACVs and furthermore, if my IACV was bad to begin with how would a ECU reset have fixed it..
Ill find out eventually. Replacing my IACV with a NEW one and will drive it a few thousand to see if it can relearn.