14 replies to this topic

[HertsMini]

Hi all, my MPI has been kangarooing/jerking at slow sleeps since I got it, some people have said to me that it's a bit of an MPI trait and other have said that it shouldn't happen or be very minor. 

 

It is quite pronounced at slower speeds - 2nd/3rd gear around 2000rpm when I'm coming on and off the throttle mainly in town. Only way I seem to be able to limit it is to be very very smooth with my throttle inputs or dip the clutch. 

 

I had the car hooked up to a code reader yesterday and no faults were showing and the live data was indicating that all the relevant sensors are working (crank, cam, lambda etc.) as far as I can tell. 

 

Any thoughts on how it could try and reduce the amount of kangarooing? New plugs? HT leads? The car has only done about 300 miles in the past 3/4 years so maybe something to do with it as well. Thanks in advance! 

 

[Wiggy]

Mine used to do it. Albeit an S conversion. I assumed it was the tall gearing and the 1.5 rockers killing the low down torque. I used to use 1st more than I liked and automatically dipped the clutch and when slowing at lower speeds.

I worked around it for a few years, but eventually changed the final drive ratio from 2.76 to 3.1. Made a big difference.

Big job though. Did it combination with a rebuilt gearbox.

[HertsMini]

Thanks for getting back to me, good to know. I probably won't be rebuilding my gearbox for some time though. I wonder if there is something not quite right with one of the sensors after changing the spark plugs yesterday. Cylinders 1 and 4 were quite badly carbon fouled while the other two were fine, not sure if it has anything to do with the kangarooing though 

[genpop]

Hi,

this might be a problem with the cables.Somebody had this problem on the german forum.In the loom there are some cable joints, some of these will corode by the time.In Your case it should be the SJ5 on bottom of page 24 in this link:

• #7

Auf Seite 24 unten ist der SJ5 ....

https://allbrit.de/d...altplan_MPI.pdf

 

when you search it in the loom it is between throttle position socket and lambda socket

You have to press or resolder it!

[HertsMini]

Interesting post, not sure how confident I’d be messing around with the wiring loom! Any idea where I can get an English version of the attached Rover tech bulletin?

Attached Files

•  B94B894D-9FA5-42B5-BCFA-B9D61DE7F74B.jpeg   35.34K   13 downloads

Edited by HertsMini, 10 August 2021 - 11:10 AM.

[sonscar]

Check for obvious things like sticky cables and linkages,is the motor well restrained with limited movement?.Too weak and/or too much advance can cause surging at low speeds as can too much acceleration enrichment but I would have no clue as to how you could measure or address this.Have fun,Steve..

[genpop]

Interesting post, not sure how confident I’d be messing around with the wiring loom! Any idea where I can get an English version of the attached Rover tech bulletin?

That is  what i wrote.The place in the loom is different.

[Wiggy]

Thanks for getting back to me, good to know. I probably won't be rebuilding my gearbox for some time though. I wonder if there is something not quite right with one of the sensors after changing the spark plugs yesterday. Cylinders 1 and 4 were quite badly carbon fouled while the other two were fine, not sure if it has anything to do with the kangarooing though

The inners and outer plugs are normally noticeably different due to way the head is designed. Even with injection. I forget which are supposed to be the sootier ones though.

I don't think a sensor would cause the issue as there's 2 injectors. One for cylinder 1 & 2, and one for 3 & 4.

I'd check the valve clearances though. You might need a new rocker cover gasket if you do.

[HertsMini]

 

Thanks for getting back to me, good to know. I probably won't be rebuilding my gearbox for some time though. I wonder if there is something not quite right with one of the sensors after changing the spark plugs yesterday. Cylinders 1 and 4 were quite badly carbon fouled while the other two were fine, not sure if it has anything to do with the kangarooing though

The inners and outer plugs are normally noticeably different due to way the head is designed. Even with injection. I forget which are supposed to be the sootier ones though.

I don't think a sensor would cause the issue as there's 2 injectors. One for cylinder 1 & 2, and one for 3 & 4.

I'd check the valve clearances though. You might need a new rocker cover gasket if you do.

 

ah ok interesting I had no idea that was the case. Funny you mention the valve clearances I actually checked them over the weekend and they were way off, they've all be adjusted correctly now. The engine definitely runs smoother and the tappets make a lot let noise but the jerking still persists. I'm going to hook up my Pscan and do a couple of runs over the next few days to see if any of the data looks off.

[HertsMini]

Update - I went for a drive the other day and was recording some data and got some strange Lambda readings (see photo). The sensor was updating very frequently with different readings as it should be but there seemed to be a 16V anomaly every 4 mins or so. 

 

Any idea what this could be? Seems very strange. Maybe related to the wiring bulletin that we were discussing earlier. Maybe forgot to mention as well but the exhaust seems to be popping, not sure if related or something else, happens when it's hot or cold. 

Attached Files

•  Lambda Data.png   82.46K   4 downloads

Edited by HertsMini, 15 August 2021 - 10:53 AM.

[genpop]

"Maybe related to the wiring bulletin that we were discussing earlier."

 

Where is the discussion?

[HertsMini]

"Maybe related to the wiring bulletin that we were discussing earlier."

 

Where is the discussion?

Even if that was the cause of the problem I don't have the expertise to start taking apart the wiring loom and soldering joints unfortunately. Maybe something I can mention to a mini specialist the next time I take it in. 

 

The German forum had some good info on SJ5 but it's not exactly the easiest thing to follow - Google translate seems to have it's limits!   Could be useful for someone with the bit more experience. 

[genpop]

Very easy, you open the wrapping of the loom between throttle position socket and lambda socket. There you will see the splicing of some cables.Find a friend who can solder that, wrapp it again and all is ok.

[HertsMini]

Very easy, you open the wrapping of the loom between throttle position socket and lambda socket. There you will see the splicing of some cables.Find a friend who can solder that, wrapp it again and all is ok.

I was actually thinking about this yesterday after I sent my last response. I will try and do it later this week. Some of the images on the German forum seem to show SJ5 as being 20-25cm from the main ECU socket on the loom is that roughly correct? I'll have a look between the TPS and Lambda sockets. I will let you know how it goes.

 

Have you done the repair before?

[genpop]

No haven`t done it myself.But one user claimed it is between throttle position socket and lambda socket. He had a picture of it.