Engine goes into limp mode occassionally

[Stuart Junior Member Find all posts View Profile Close Stuart]

Hi Folks,

(Sorry this is so long, but I'm logging it for me too)

I'm seriously hoping that someone may have an idea of what is going on as we're at the end of our rope here.

We have a 120 D4D. It has almost 270ks on the clock. It's been serviced to the log book and beyond like clockwork. This is a really well looked after vehicle. Most of those ks are highway ks too.

Around January last year, I was driving home from work when I lost power after driving on the expressway for about an hour. I was parked at the lights and the car just would not go over 20 no matter how hard I pushed the accelerator. I put the hazard lights on, and started to pull over when WHAM! Off it went. I continued on for a while, dropped my son off at school and then it just completely turned off going down a hill. I have a scan tool and no errors were being thrown. I waited a few minutes and started it again and there was no issue. Everything looked fine.

I drove over the mechanic who had no idea. His scan tool showed nothing. So I went home.

Fast forward a month, and it did it again. Three times. Again no error code, and the car started just fine after doing it. Again, mechanic couldn't tell what it was. We started to suspect EGR issues, so I ran a treatment of Fuel Doctor for a while, and that seemed to fix it up. For the next 3 months it was perfect.

Then we went on holidays towing our camper. We went from Newcastle to Mildura without a problem. Spent a week driving around there without a problem. The day we were due to leave to head up to Broken Hill it did it. We had no option but to push on. It did it again crossing flood water at Menindee Lakes just out of Broken Hill. And then it was fine while we were there until the day we left. My wife was driving on the hwy and and went to overtake a road train. She got about 100m in front of it and it went properly into limp mode. This time the engine fault light came on and we absolutely packed our dacks. This must have been the only section of highway that we could pull over on which didn't have an embankment. Pulling over, I check the error - P2006 (https://www.autocodes.com/p2006_toyota.html).

The error seemed non critical, and the engine started OK, but still kept the engine fault light on. We decided to push on. The car would stall when going up pretty much every hill (we worked out after the 10th time that if we drove in 4th the problem wouldn't happen). We got home after 12 dreadful hours.

It went into the mechanic again the next day. Again, nothing found. Cleared the codes and we decided to look at getting the EGR done, the intake cleaned and whatever.

After a discussion with my dad, he knew someone at Toyota who was happy to take a look. The mechanic wasn't able to look until after Christmas, so being able to get it done in late November was appealing. Toyota took off the intake manifold and sent it off for cleaning. It was so clogged it needed two rounds of cleaning. The EGR was also cleaned. And they found a vacuum pump wasn't working, so that was replaced too.

When we got it back, it was fantastic. Drove pretty much like new. For about 2 weeks. Then as I drove, I could feel the car kind of 'spluttering'. Like a petrol car with a dirty carb or spark plugs. It was only noticable I guess cause I was waiting for it. Then last week, it started again. No power on take off after driving at a speed over 100 for a while. I pulled out into traffic with plenty of room to spare and it cut out causing quite a lot of angst as we almost got rear ended.

We've done the following:

Replaced front and rear fuel filter
New fuel pump
New air cleaners
New vacuum pump
Clean of EGR
Clean of intake manifold

I can't remember what else we've done, but it's costing us a fortune. I am hoping someone may have clues as what else we could be looking at. The only thing really left I think are the injectors. But not really convinced that they are the problem either.

Thanks for anything you can add.

Stuart.

[ptommo59 Senior Member Find all posts View Profile Close ptommo59]

Hi Stewart,

Not certain of your Model year but from a quick scan of the 1KD-FTV Repair Manual I can access - A P2006 code in isolation is most likely linked to a leak/blockage in the intake air system and/or stuck/closed Swirl Control Valve in the inlet manifold.

Extract from manual as its too big to upload the pages:

If the actual volume of air at the intake measured by the mass air flow sensor continues to be less than the volume calculated from the boost pressure and the intake air temperature sensor reading, the ECM determines that the suction control valve has jammed in the closed position.

Causes:

• VSV for suction control valve
• Break or short circuit in the VSV circuit for suction control valve
• Intake manifold (suction control valve)
• EGR valve assembly
• Turbocharger assembly
• Mass air flow sensor
• Air filter hose
• Vacuum hose
• Clogging of the filter element of the air filter
• Disconnection of the intake hose
• ECM

Being intermittent it would be worth checking your vacuum hoses around the swirl control valve/solenoid in the picture below, wiring to the solenoid and then the main components.

Hope this helps at least confirm or eliminate this potential cause.

PS: The vacuum pump Toyota changed provides the vacuum source to the solenoid so could have been your original issue for the code. The pump could have failed due to overcycling because of a leak so it could all make sense.

Also check out this video as it may also be useful linking the two issues even though it's the solenoid causing it in his case Toyota D4D 3.0 Limp mode problem & repair advice - YouTube

[Stuart Junior Member Find all posts View Profile Close Stuart]

Hi

ptommo59

Senior Member

Find all posts

View Profile

Close

ptommo59

Thank you for the long post with so much detail in it! This was super helpful and quite interesting. I have more info now though, plus a cause and fix.

We took the Prado back up to Toyota after the issues I raised above. They went through it again and found a sensor (I can't remember what it was, but will update this post once I find the invoice). That seemed to make a difference - for 2 weeks. May in laws kept the car with them and drove it daily (some days doing 350+kms). It did not miss a beat. So we organised to catch up, and it died half way down to us (they live 200kms away from us and it died about 120ks from them). So they took it back to Toyota about 2 weeks before Easter.

When I died this time, it threw another engine fault with the engine light. The code this time was P1229 (which is different from the last 3 times when it threw P2009). This is the report:

Scanned for fault codes - P1229 Fuel Pump System current and historical
Followed through diagnosis - fuel overfeed as per repair manual.
Checked data list, found suction control valve not working intermittently.
Checked wiring harness and inspected suction control valve - OK.
Pulled down fuel tank to check fuel plate assembly, found strainer on fuel plate to be blocked.
Requires replacement fuel plate assembly, fuel filter and sub tank fuel filter.
Removed and replaced fuel filter, sub tank filter and fuel plate assembly.
Test drove OK.

So far it has done almost 1000ks since the work was done, and seems to be running better than ever. I've even noticed the economy has improved a bit, more power and idles much quieter than it did before. It wasn't a cheap fix. $2700 for this one. When you add in the $1400 for the first job and $300 for the second, it's certainly been a bit expensive. But if it's fixed it, I'm happy.

We did ask them to check out each of the items you listed above. They were impressed that someone knew all that. I hope your detailed post helps someone else even if it wasn't the problem with our car in the end.

Cheers!

Stuart.