RD28 - loss of power - very sensitive accelerator pedal

[Mike_1]

Hi all,
So I bought a 1998 GU RD28 Patrol, but I'm having issues with it:
- accelerator pedal is very sensitive, if I touch it just slightly it goes straight from idle 700rpm to about 2500rpm, i'm not able to increase revs just a bit, but when I hit the pedal all the way down it will rev up to 3800rpm
- if I hold the accelerator pedal in a certain position it will jump intermittently from 700rpm to about 2500rpm, even on idle.
- car is very slow, I had trouble going up the hill on M1 from Newcastle to Sydney doing only 60km/h
- car does NOT overheat
- it has an aftermarket MAF installed, which is plugged in a very messy way near the ECU inside the cabin
If I unplug the MAF while idling should I notice any difference in rpm etc?
- I have replaced the accelerator pedal assy with my mate's one thinking this might cause it, but issue remains - no change at all.
- apart from that I absolutely love it

Cheers
Mike

[P4trol]

Car will idle without the maf, but if you drive off, it won't boost - there's no way you won't notice the lack of power.

Could I encourage you to try a genuine 'new' maf sensor?

[BigRAWesty]

Do you know if the 98 GU has a electronic peddle or is it still cable?

[Mike_1]

Electronic mate, but like I said, I swapped it already with another working one, but issue remains.

[Mike_1]

Sorry for a massive delay, but I was recently moving units.
I had a chance to look deeper and investigate the issue in my spare time, here is what I've found:
- i've hooked up my patrol to the diagnostic interface and it reported issue using ECUTalk: Code 43: Accel pos sensor
- i've followed troubleshooting for error code above using GU Repair manual and RD28 service manual
It linked me to ECU harness connector 23, where there should be continuity between the accelerator position sensor plug (middle pin, white cable) and pin 23 on the ECU harness - there isn't! Next, i've uplugged ECU harness and to my surprise, guess what, there is not pin 23 in my harness! It doesn't look like previous owner has removed it on purpose, as there is too much hassle to remove the pin itself.

Can someone with RD28Ti can confirm that they do have pin 23 occupied?

Thanks
Mike

[P4trol]

Did you always have the 'sensitive pedal' issue, or has it appeared during your term of ownership?

[Mike_1]

I bought this patrol two months ago and it was like that already.

[threedogs]

Yendor may be your man on this issue.
May sound stupid but have you tried dis-connecting the battery for a while?

X 2 clean or fit new Maf or swap with a known good one

[P4trol]

If a sense such as maf or the one in the intercooler isn't connected, you would notice. No maf connected results in no boost, and sslloooow acceleration. I had an aftermarket maf, and changed it for a new genuine. (inside was a broken wire, and some clear home modifications - no wonder it didn't work properly)the sump oil leak is now a lot less. It accelerates heaps better at 100km/h. I recently took out the intercooler to clean, and did not correctly reconnect the (temperature?) sensor. It just didn't have as much 'go'. I fixed it, and it is back to normal. In short, the ecu uses all these readings from the sensors to make important decisions about the engine.

I haven't looked, but I believe the service manual details how to test the accelerator pedal (which is a sensor)

[threedogs]

X 2 P4trol it may even be a bad earth issue which patrols are famous for.

[Mike_1]

Thanks for all the feedback, i'll look into it later on this week. What concerns me is if anyone with RD28Ti could confirm that they have ECU harness PIN 23 present or not.

[threedogs]

PM ronnieY61, plus read his thread he may be able to put you in the right direction

[P4trol]

Page EC109 in the 1998 manual details tests to make sure the accelerator switches is working ok.

(diagnostic trouble code DTC 23)

Coincidentally the pin number you seek is also 23.

[P4trol]

So I have done a bit of reading myself. A few things stick out.

When working out which pin is which, work from the side of the connector which has the wires going into it. (pop off the plastic hoop that protects the wires entering the back of the plug.) The back of the plug, if you think of it that way.

37844

Above you have pin 23, top row, fourth wire from thumb (sorry about poor quality of pics, am on phone)

37845

Above my thumb is close to the other side, which you may have mistaken for pin 25. It could be you are trying to read the pins from the side of the plug pictured below. The numbering is backwards if you are trying to do it this way.

37846

Anyway, if you are doing the tests with it plugged into the ecu, stick your probe down the back of the wire.

I doubt the pins you are after are missing.

Edit: to get perspective on the first two photos, in the bottom photo there is a ridge in the Rh side of the connector. This ridge faces the camera in the first two photos.

[Mike_1]

P4trol - you're an absolute legend! I read the ECU harness diagram incorrectly, by the looking at the end of it, not when it's plugged in! I traced that wire, which was connected to god knows only where, connected to the proper accelerator position sensor and tested. IT WORKS! I'm getting full range of RPM's, pedal is smooth as! I haven't done test ride yet as whole harness is floating around the pedals, but I'll do it first thing in the morning and let you all know! Thanks once again!