[Kory Nunn]

Figured I'd document my saga of resolving the hunting idle issue my 06 Gallardo gets when the car is warm, usually when in start-stop traffic. I've had this issue since I got the car a few months ago. Lots of others seem to have this issue so it'd be amazing to figure out what's going on and resolve it for everyone.

The car performs perfectly under throttle, I recently did a track day, and did 3 sessions out on track, with a lot of WOT, and it never missed a beat.

On the way home I hit traffic, and the idle started hunting. After about 20 mins of traffic I got onto the highway, but after a few minutes the car shut down 1 bank, and then the second. I pulled over for about 1-2 minutes, restarted the car, and it drove fine, if a bit sluggish, the rest of the way home (~15mins). I'm guessing the idle threw out trims, and caused issues under partial throttle on the highway.

I've also monitored fuel trims via OBDII when this happens, and they go all over the place.

Things it isn't:
1. Fuel pumps, both replaced.
2. Spark plugs, all replaced.
3. FPR (at least not Bank 1), replaced, and swapped back.
4. O2 Sensors - both replaced.
5. Intake heat-soak: Intake wrapped in gold heatwrap, IAT's observed to be ~40deg, down from ~60deg observed via OBDII
6. Injectors - Replaced with brand new Bosch, no change.
7. Evap purge/fresh air issue - Tested working
8. Coil packs - Replaced with brand new NGKs
9. MAP sensor - Replaced with brand new Bosch
10. Vacuum leak - Sprayed ether all around the engine bay, no change to idle.
11. Throttle bodys/TPS - Thoroughly cleaned, including teardown of TPS/clean/check not worn out

Things I'm now 99% it was:
- Bad Cats/Doughnut gaskets
- Both cat cores had detached from the walls, were moving around, and had bits missing:

- Both header -> cat gaskets were either in very bad condition or completely broken:

New cats + moved the better condition rear gaskets to the front, and idle is much improved.



Original post:

I'm currently replacing all injectors, removed them all last night, and am waiting for the new ones to arrive.

For the most part, the injectors look in very good condition, no gunk, very clean, all O-rings are still very compliant.

This was the worst one and the one I think is most likely to have been causing issues, it looks like grime has been able to get past the O-ring, which would imply a vacuum leak, which could definitely cause idle issues.

If the new injectors fix this, I suspect this will have been the cause, and all I really needed was to replace this one O-ring, but new injectors wont hurt after nearly 20 years.

 

[mr_engineer]

Im not a first gen guy.. But look into the throttle body issues.

 

[LpZero]

A few threads about how the strip in the throttle bodies can lead to surging at idle. An "idle hunt" is hard to internet diagnose but you are tackling the proper things. Vacuum leak somewhere or dripping injectors.

 

[Kory Nunn]

Updated post, I don't think its the throttles but we will see. I'd expect to see them moving and "missing" the target position if it was the resistor strip in the TPS.

 

[ablettdc]

I had a little idle hunting while at idle with my Sprint Booster attached. I contacted Jason B about it and he had me return mine for another updated version with 2nd day air shipping. No idle hunting since installing the new unit. Will follow this thead in case other culprits arise in the future.

 

[4xchamp]

I had a little idle hunting while at idle with my Sprint Booster attached. I contacted Jason B about it and he had me return mine for another updated version with 2nd day air shipping. No idle hunting since installing the new unit. Will follow this thead in case other culprits arise in the future.

Lose the booster, it will eff up everything. You're playing with fire and assuming significant exposure.
Updated version!? Lol

 

[4xchamp]

The guy is a charlatan. Sent you the wrong version? Okay

 

[ablettdc]

The guy is a charlatan. Sent you the wrong version? Okay

Wrong on both fronts. I reached out to him because of his presence in the exotic car parts space and without hesitation had me send him mine and told me where to send it and sent the second next day air. After we got it all sorted out I found that I had purchased it from another vender and he didn't even blink. He went way above and beyond with no skin in the game nor any culpability. I am not sure what evidence you have for suggesting I am "assuming significant exposure" but that should be a topic of another thread not this one.

 

[GrayFoxMGS]

Wrong on both fronts. I reached out to him because of his presence in the exotic car parts space and without hesitation had me send him mine and told me where to send it and sent the second next day air. After we got it all sorted out I found that I had purchased it from another vender and he didn't even blink. He went way above and beyond with no skin in the game nor any culpability. I am not sure what evidence you have for suggesting I am "assuming significant exposure" but that should be a topic of another thread not this one.

Wasn't Jason booted from an Facebook group admin position for deleting negative reviews of the exotic car parts he sold? There was also a user on these forms who was promised a refund but was continually dodged until Jason's "sister" happened to see the posts about him and chimed in. Apparently Jason had a family member in the hospital and wasn't able to respond for many weeks. Its a good thing that I sister happened to create a Lambo Talk profile and update everyone on the situation though .

I also recall another user who was upset about his "carbon fiber" wing that arrived that was made of fiberglass and required work to get it to even fit. This was after two other body shops declined the spoiler install as well. Truly, it was a drop shipped $500 Chinese wing marketed as something that's a legitimately awesome product. Then there's the decade old 4 Runner forum posts about Jason where guys even all those years ago had problems.

I've ordered from Jason myself but ultimately I wish I knew who he was drop shipping from before making the purchases hahaha

 

[ablettdc]

I've ordered from Jason myself but ultimately I wish I knew who he was drop shipping from before making the purchases

Me too. This goes for all Lambo parts suppliers!

 

[4xchamp]

I am not sure what evidence you have for suggesting I am "assuming significant exposure" but that should be a topic of another thread not this one.

I'm in the automobile industry and relating my experiences.
You're welcome to message me for my number.
Good luck.

 

[Kory Nunn]

Update: New Bosch injectors in, no significant change. Car feels like it's running slightly healthier, and at first I thought it was resolved, but I let it sit and idle after a drive for about 5 minutes, and it began to surge significantly, before one bank just died. I turned it off, and re-started it, and the second bank came back, I could hear it start about half a second after the first bank.

Scanned for codes and got a P1106, which checking the shop manual is:
MAP/Barometric pressure - Comparison between ECU bank1 value and ECU bank2 value > 25mmHg for >4s

It's hard to know if this code points the the cause or is just a result of one bank not firing.

I found this thread where another owner had the same code caused by one exhaust valve not opening, but I don't have a valved exhaust. I do however have original cats, and if one is really clogged up I could see that causing issues when warm.

One question I have is: how/where is the ECU measuring barometric pressure? Is it just on the MAP sensor, or do the ECU's have onboard sensors?

 

[Bully69]

Decat it as a priority imo!

 

[LpZero]

Have you tested your intake runner valve? Could be torn, it's the rubber thing down by the oil filter that changes intake length using vacuum.

 

[B-Dub]

I had a little idle hunting while at idle with my Sprint Booster attached. I contacted Jason B about it and he had me return mine for another updated version with 2nd day air shipping. No idle hunting since installing the new unit. Will follow this thead in case other culprits arise in the future.

I've noticed the same thing with my 2004 with a sprint booster, especially in the warmer months when running the A/C. I can turn the SB off and it hunts much less, but it's a bit of a pain to turn it off & on when at stop & go traffic, lights, etc. My SB is about 2 years old.

 

[4xchamp]

I've noticed the same thing with my 2004 with a sprint booster, especially in the warmer months when running the A/C. I can turn the SB off and it hunts much less, but it's a bit of a pain to turn it off & on when at stop & go traffic, lights, etc. My SB is about 2 years old.

I'm curious. Have you tried deleting the sprint booster to see if there is an improvement?
Is yours a stick or an Egear?

 

[4xchamp]

Update: New Bosch injectors in, no significant change. Car feels like it's running slightly healthier, and at first I thought it was resolved, but I let it sit and idle after a drive for about 5 minutes, and it began to surge significantly, before one bank just died. I turned it off, and re-started it, and the second bank came back, I could hear it start about half a second after the first bank.

Scanned for codes and got a P1106, which checking the shop manual is:
MAP/Barometric pressure - Comparison between ECU bank1 value and ECU bank2 value > 25mmHg for >4s

It's hard to know if this code points the the cause or is just a result of one bank not firing.

I found this thread where another owner had the same code caused by one exhaust valve not opening, but I don't have a valved exhaust. I do however have original cats, and if one is really clogged up I could see that causing issues when warm.

One question I have is: how/where is the ECU measuring barometric pressure? Is it just on the MAP sensor, or do the ECU's have onboard sensors?

You have two mass air flow sensors (MAF). With a scan tool view live data to compare MAF readings on the two banks. Be aware they do fail but on occasion just need to be cleaned with MAF spray cleaner.
Also check for vacuum leaks.
I've seen the air tubes between the throttle body and air filter dry rot and get cracked. This introduces air downstream of the MAF sensor that is not being metered and will throw things off.
I'll also urge you to consider my previous suggestion and eliminate that as a culprit.

 

[Kory Nunn]

You have two mass air flow sensors (MAF). With a scan tool view live data to compare MAF readings on the two banks. Be aware they do fail but on occasion just need to be cleaned with MAF spray cleaner.
Also check for vacuum leaks.
I've seen the air tubes between the throttle body and air filter dry rot and get cracked. This introduces air downstream of the MAF sensor that is not being metered and will throw things off.
I'll also urge you to consider my previous suggestion and eliminate that as a culprit.

Mine is a pre-lp and has no MAFs only one MAP.
Mine also does not have a sprint booster.

 

[ablettdc]

I replaced both of my Throttle Bodies with used units that the seller assured me were 100% functional when removed from the car to go to a Motec twin turbo setup using other TBs. I cleaned both sets and made sure my gaskets were not leaking. I noticed about 50% less idle hunt at that time with all else being unchanged. I have read that others have reported idle hunt resolved after doing the Sacer 100 Contactless Throttle Position Sensor (TPS) via XeModex in Canada. I will likely do the contactless TPS mod to my old Magnetti Mirelli TBs to see if that makes any difference.

 

[Kory Nunn]

Have you tested your intake runner valve? Could be torn, it's the rubber thing down by the oil filter that changes intake length using vacuum.

Have not yet tested, I'll do a smoke test which should reveal that. They do suck in and affect the intake runner valves so they can't be too bad.