Toyota 100 series and DP Chip problems

Submitted: Thursday, Apr 01, 2021 at 21:21
ThreadID: 141329 Views:846 Replies:3 FollowUps:5
I have a intermittent problem , five times in 10,000 Kms the cars engine management light comes on and a couple of kms later the car goes into limp home mode. The problem only has occurred when towing a 2.5 ton caravan and driving uphill, usually in 4th dear ( its a 5 speed auto ) its a 2006 1HD FTE 230,000 km
I turn the engine off and 10 minutes later all is good. My mechanic said it is a throttle body error code, which lots of things can cause. He could find no hose or wiring issues .He suggested removing the DP Chip when it next occurred, I did that on the next occasion and retackled the same hills . No problem. Put the DP chip back in and drove the same hills slowing down to 40km then flattening it in 3rd gear to 3500 RPM . Of course the problem didn't reoccur.
I consider it is not a heat or vibration issue as all occurances have being on the bitumen not offroad.
So I would like to know if anyone else has had similar issue with the DP chip or any other ideas
of possible cause?
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Reply By: RMD - Thursday, Apr 01, 2021 at 22:30

Thursday, Apr 01, 2021 at 22:30
Pedro
You didn't say if you still had the van on when testing with and without DP chip. In no van then the boost level would be far less than with the van. Since the DP chip tampers with ECU signals and according to your mechanic, a Throttle body code is generated, then it would seem to me to be air flow or boost related issue. If the parameters of the ECU program are exceeded for a set period of time the ECU will throw a related code. Do you know the code?
I see you took it to 3500rpm but that isn't at the speed and associated load with the van on. Higher revs may produce less boost than pulling in 4th at lower speed. Did the testing still have the van on the back up the same hills?
AnswerID: 635833

Follow Up By: Member - pedro1 - Friday, Apr 02, 2021 at 19:23

Friday, Apr 02, 2021 at 19:23
RMD Thanks for your reply, all the driving was done with the van on, it took only 10 minutes for me to read the code DTC 15 by shorting out the MOB11 plug , disconnecting the battery to clear code and pulling out the DP Chip then retracing my route , my mechanic said previously it was P1222 on his device - Throttle Control Motor Circuit Malfuctionhttps://lc100e.github.io/manual/rm/rm896e/m_di_0023.pdf .
I then did replaced the DPchip back into the circuit and retraced by route again.
I therefore eliminated heat as the cause
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FollowupID: 913551

Reply By: Mike C9 - Friday, Apr 02, 2021 at 13:00

Friday, Apr 02, 2021 at 13:00
Hi Pedro

I have a 2010 Prado and I fitted a DP chip several years ago. It started giving me the same problem that you described however, when I disconnected the chip but left the wiring connected, it still did the same thing (intermittently). After removing the DP chip wiring, the problem went away.

I took the wiring loom to Berrima Diesel, where I bought the chip, and Andrew found some dirty contacts in one of the plugs. He cleaned them and the problem disappeared. I reinstalled the chip and did a Sydney to Cape York trip towing a 2.5t van without a problem.

Six months later, I was driving without towing and the engine blew a hole in #3 piston! $13000 later after a complete engine rebuild, the chip and its wiring have been removed and never reinstalled. The original pistons were replaced with forged pistons and the injectors were replaced with "upgraded" items from Baileys in Wollongong. The guy that did the rebuild suggested that the chip was a contributing factor to my problems.

That was five years ago. I've since towed the same van to Darwin and back, the Grampians in Victoria and lots of other places and I believe that the engine performance is as good if not better than with the DP chip.

Mike
AnswerID: 635844

Follow Up By: Member - pedro1 - Friday, Apr 02, 2021 at 19:33

Friday, Apr 02, 2021 at 19:33
Mike, thats sounds scary . I wonder how you disconnected the chip but left the wiring connected ?
I have had to disconnect the DP chip wiring to plug the original wiring back together.
A couple of months ago I also inspected the DP Chip wiring as part of my fault finding and found some corrosion on one of the DP Chip plugs. I got a auto electrician to replace the plug and to also replace the inline DP Chip fuse in the effort to eliminate possible causes
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FollowupID: 913552

Follow Up By: Mike C9 - Saturday, Apr 03, 2021 at 09:35

Saturday, Apr 03, 2021 at 09:35
Pedro

My DP chip came with what I would call a loopback or turnaround plug. The instructions said that if you want to remove the chip for any reason the plug could be inserted in its place and it would loop the wires from the injectors back as if the loom wasn't there.

It may be different on the 100 series.

Mike
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FollowupID: 913562

Reply By: Gronk - Friday, Apr 02, 2021 at 22:05

Friday, Apr 02, 2021 at 22:05
If it does it again with the chip installed, take it out for a time period that lets you do several trips with the van and then see if it reoccurs.
No more faults, ditch the chip.
AnswerID: 635856

Follow Up By: Member - pedro1 - Saturday, Apr 03, 2021 at 00:22

Saturday, Apr 03, 2021 at 00:22
Unfortunately it is so intermittent, to give you a idea, in the last year, first occurance was on the Gt Ocean Rd Vic. No issues in Tas , then next were all in WA - firstKarratha , then Margaret River and finally south of Geraldton last week.
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FollowupID: 913556

Follow Up By: RMD - Saturday, Apr 03, 2021 at 15:35

Saturday, Apr 03, 2021 at 15:35
Pedro
It really does appear to me to be the chip causes some over parameter in the ECU under specific conditions and then runs a code. The ECU will of course run a code if the condition remains for a set ECU time period after the light warning initiates. Only by closely observing Speed. load, throttle opening, etc, at that time will it give any idea as to what is the cause. As you said, hard to find.
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FollowupID: 913581

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