41 replies to this topic

[brivinci]

One other thing: so I am a lifetime Apple user which doesn't help that all these diagnostic programs are Windows based. Compete user error but I was only able to get things to run and log using an old Samsung phone my father was getting rid of. All that said, that is what I used to see the above readings. Came back in and saw that rovermems.com now works with Mac so I gave that a go. Hooked and checked the TPS and readings only go as high as .995v, with a low of .12 BUT seems to sit at .25v unless I snap the throttle closed. 

 

Why on earth would I get such a low TPS volt reading using a laptop vs using a phone. Same cable. Maybe there is something up and your TPS (although still sticking) is giving the correct voltage reading, especially given the 5v supply you tested.

[Mayfair94]

Okay I have some brand TPS NOS  I shall check them out and let you know. Please check using ohms reading as I’m not able t9 connect to the car. 
I have recently had a club member with a loom which had burned through connections at the bulkhead which showed low voltage due to the loom - might be worth checking continuity from ECU to TPS connector.

 

FS

Thanks FS, I would very interested to see your readings as I was getting a steady increase in resistance but between any of the 3 pins. Interested to hear your values. I will do a con check on the wires from the ecu to the sensor, especially the signal line. Will try and chase back the loom and look for any obvious chafing that may have broken down the insulation. 

[Mayfair94]

One other thing: so I am a lifetime Apple user which doesn't help that all these diagnostic programs are Windows based. Compete user error but I was only able to get things to run and log using an old Samsung phone my father was getting rid of. All that said, that is what I used to see the above readings. Came back in and saw that rovermems.com now works with Mac so I gave that a go. Hooked and checked the TPS and readings only go as high as .995v, with a low of .12 BUT seems to sit at .25v unless I snap the throttle closed. 

 

Why on earth would I get such a low TPS volt reading using a laptop vs using a phone. Same cable. Maybe there is something up and your TPS (although still sticking) is giving the correct voltage reading, especially given the 5v supply you tested.

Thinking about it, you may be onto something there. I managed to use a different program today that didn’t give TPS voltage, but it did give a Throttle percentage and with the throttle fully to the floor I got 96% so in theory it must be getting the correct volts to indicate full throttle? This program also confirmed that the throttle would stick around the 30-40% mark depending on how quickly you released the spring, which is the same with it off the car. Maybe the rover mems programmer (the program I initially used also) has made it a scale of 0.0 to 1.0 and not and actual voltage reading?

 

I could try and get a voltage reading from the back of the plug but it is nicely sealed and I’m reluctant to break into it.

Edited by Mayfair94, 21 December 2020 - 10:35 PM.

[brivinci]

Yes!! That must be it! A percentage rather than a voltage reading. I probably just assumed it was voltage because that was what I was looking for. 

 

What programs are you running exactly? I was using this (https://rovermems.com/#ecus) on the laptop and an app called MEMS Diag on the android. They might be from the same place but I cant remember at this point.

[Mayfair94]

Yes!! That must be it! A percentage rather than a voltage reading. I probably just assumed it was voltage because that was what I was looking for. 

 

What programs are you running exactly? I was using this (https://rovermems.com/#ecus) on the laptop and an app called MEMS Diag on the android. They might be from the same place but I cant remember at this point.

I was using the Rover Mems Diagnostic web based program (your 1st link) when getting the 0.95v. I have a couple of others now loaded to my laptop, MEMS Rosco and MEMS Gauge. I was going to see what they showed today but being a numpty I left the keys in the ignition and the battery is goosed. I was expecting to have to buy a new one at some point as it was the one that came with the car 5 years ago and has been sat in my garage all that time. It did take a charge but now it’s as flat as a pancake it just comes up with a fault light. Planning on putting a HB075 in the car as the old one was a HB038 and quite small for a 1275.

[Mayfair94]

Just as a visual, not sure if the video will load, but I videoed the TPS sticking half way which it does every time. Hopefully getting a used one locally and see how that goes.

 

 trim.B95A3AE3-2C60-4790-9C56-3B3C1EAADF71.MOV   806.77K   30 downloads

[genpop]

@brivinci

there is a beta version of mems-rosco on github.com/leopoldg

You may see your logfile as a list!

additionally you may search for " car mechanic magazin october download." page 86 rover mems diagnostic!

Edited by genpop, 23 December 2020 - 07:28 AM.

[brivinci]

Fired up the ol PC and tried to download but couldn't. Maybe its this wonky old Dell I am on...but probably just me. As I said, windows is soooo foreign to me. It won't let me download everything at once, I am not even sure I am supposed to. I tried the .exe and car files but they need others. I'm going to have to try this on another computer and see if its just this piece of junk I have.

[Mayfair94]

While I wait to get a replacement TPS, I went out today and just plugged the old one back in so I could control the arm myself. I loaded ROSCO today and the readings for TPS are clearer. At idle 0.2V and full throttle I got 5.0V so the potentiometer works fine, it just doesn’t spring back to idle so needs replacing.

 

With the engine running, I started playing about with the IAC settings on ROSCO. The 1st button I pushed advanced the throttle to over 1700 rpm. I then reset it and the engine started hunting to the point of almost stalling. In the end it started idling at about 700 rpm until I exited ROSCO and it went back up to its usual high idle of about 1150 rpm. I then went into the web based Rover Mems Diagnostic and there you can decrease idle which I did down to approx 950 rpm. It then seemed to idle nicely here.

 

I suspect the whole throttle system and IAC need setting up properly although from reading these forums I gather that is going to be pretty difficult without the Sykes diagnostic equipment. When the replacement TPS is in I will do the Haynes setup for the throttle adjustment, but if my idle needs adjusting I’m guessing I may need to find someone with the correct equipment?

[genpop]

Hi did you use the beta version of mems-rosco? There was a bug on setting the IAC in the old version. As well for normal users it is recommanded to do only a reset of the ecu.

[Mayfair94]

Hi did you use the beta version of mems-rosco? There was a bug on setting the IAC in the old version. As well for normal users it is recommanded to do only a reset of the ecu.

I don’t think I used the beta version, I could only find 0.1.12-Windows. That is the one that comes under latest release.

[genpop]

look at github.com/leopoldg

you have to unzip twice

[Mayfair94]

Right, feel like I am making some steps forward now. I collected the replacement TPS and have now fitted it. While I was in the area of the TPS, I thought I would adjust the throttle cable/stepper motor to get the lost motion arm in the correct position. With the stepper set in the correct position it was quite a bit out. I adjusted the cable and could just about get the arm in the middle, but I was at the end of my adjustment. I suspected the cable may have been old and stretched hence why I have no more adjustment left. I put it all back together and the TPS is now reading smoothly up to full throttle on the stop.

 

I started the engine and idle was still high, in the region of 1100-1200 rpm. However, when accelerating now there was no hesitation, stuttering or popping as there was before. That left me with the high idle rpm to sort. With the throttle pedal returned to the idle position, I then carefully lifted the throttle with my foot and straight away the engine idled at 850 rpm. Having read the forums on here, I suspect I also have a throttle cable sticking which is the cause of the high idle. That will be my next item to replace and hopefully the final fix for my issues.

 

Thanks for all your help on here. I think I have found three things that needed to be corrected causing my issues. The TPS was sticking at 30-50 % throttle. The cable was not adjusted correctly (maybe due to age/stretched/stiff) and I also suspect the throttle cable needs replacing as it is sticking. So both electrical and mechanical faults. When I get the cable replaced I'm hoping that is it to get the engine running smoothly.

[Pops_Guild]

Right, feel like I am making some steps forward now. I collected the replacement TPS and have now fitted it. While I was in the area of the TPS, I thought I would adjust the throttle cable/stepper motor to get the lost motion arm in the correct position. With the stepper set in the correct position it was quite a bit out. I adjusted the cable and could just about get the arm in the middle, but I was at the end of my adjustment. I suspected the cable may have been old and stretched hence why I have no more adjustment left. I put it all back together and the TPS is now reading smoothly up to full throttle on the stop.

 

I started the engine and idle was still high, in the region of 1100-1200 rpm. However, when accelerating now there was no hesitation, stuttering or popping as there was before. That left me with the high idle rpm to sort. With the throttle pedal returned to the idle position, I then carefully lifted the throttle with my foot and straight away the engine idled at 850 rpm. Having read the forums on here, I suspect I also have a throttle cable sticking which is the cause of the high idle. That will be my next item to replace and hopefully the final fix for my issues.

 

Thanks for all your help on here. I think I have found three things that needed to be corrected causing my issues. The TPS was sticking at 30-50 % throttle. The cable was not adjusted correctly (maybe due to age/stretched/stiff) and I also suspect the throttle cable needs replacing as it is sticking. So both electrical and mechanical faults. When I get the cable replaced I'm hoping that is it to get the engine running smoothly.

 

Very glad you got to the bottom of it! On cars this age its common for there to be a few things conspiring against you :)

 

One word of caution with replacing the accelerator cable, if you don't know how long it was since it was replaced then there's a chance that it might have corroded itself to the ferule that it seats into as it goes through the bulkhead. This is in a really awkward place to get to and see but I would advise that if the cable doesn't seem to want to come out easily then give it a good squirt of plusgas or similar and leave it. Be patient, hopefully it will ease up enough for you to remove it. What you don't want is to use brute force (as I did) and pull cable and ferule out! ...that path leads to much hassle!

[Mayfair94]

Thanks for the advice Pops_Guild, will start the plusgas soaking process before I start the job, cheers.

Edited by Mayfair94, 29 December 2020 - 04:09 PM.