Auto Gearbox - under 2000rpm jerkiness

[mikeonb4c]

I live in the new forest. The garage I've been using have bongo experience but they probably wouldn't describe themselves as specialists. The fault does limit the distance I van easily travel.

Bell Hill have a recovery truck. Straight up the A36 from you.

Worth getting it sorted once and for all

Good advice I think, albeit that it's more outlay. You could phone them first, describe the symptoms and exactly what has been done to date, and they might be able to give you some feel for how confident they are that they can get it sorted whatever has already been tried. Good luck - you deserve some

[Bongo Virgin 2]

Thanks for those suggestions. I'll contact them and see what they say. The Bongo came from a dealer in Southampton who sells lots of V6 Bongos so I might give them a try too. If I can find the time I fancy a fiddle myself.

[Northern Bongolow]

you state above that its ok until the fans have cut in 3 times then the jerkiness starts, is this normal that the fans should cut in often on the v6. maybe the other v6 guys could comment.
just thinking that its the fan switch faulty,reading wrong then telling the other components to act in error via the ecu.

[Bongo Virgin 2]

A good point, but I don't know if the sensor sends any signal to the ecu. The fan cutting in so often may be because it's idling in the garage workshop rather than out on the open road. It is so long since I have had the car to drive that the symptoms I describe are what I had originally been investigating back in October. From description I think they are still the same but I'm not sure about the road speed lifting the revs over 2000 and the engine then running ok.

[Bongo Virgin 2]

Right, I have my Bongo back and I'm interested in the Advance/Retard system on it. I'm going to do a little investigation before I look at spending more money or sending it away anywhere else.

Does anyone know how the Advance/Retard works on the V6 Bongo? Is there a specific sensor plugged in somewhere that feeds to the ECU or does it pick up readings from the o2 sensor or Engine Temp' Sender unit and then allow the ECU to do it?

I'm pretty sure there is no mechanism in the Distributor to control it.

Thanks ver much.

[g8dhe]

Well the Ignition coil is driven from the PCM/ECU;

and the various sensors all feed the PCM/ECU, Temp. O₂, TPS;

[Bongo Virgin 2]

Thanks very much for the diagrams. I can make basic sense out of those but am not sure as to which sensor is which.

I have contacted DCP Tuning to see whether they can re-map the ECU to correct a fault with Advance/Retard, if it has one.

The Lambda, Temp' Sender Unit, Throttle position sensor, engine Temp sensor etc have all been checked or changed so I'm wondering if the ECU has gone wonky on that part of its operation only.

Having now got the car back I know it is still fine when driving over 2000rpm, hot, but undriveable below. Road speed needs to be used to get the Revs up.

[g8dhe]

The easiest way to identify the individual sensors is to go to the Index pages and select what you want, noting the code number, the physical locations are on the page following the diagram itself.

[Northern Bongolow]

there must be some sort of rev sensor, crank or cam. maybe this is the problem.

[Bongo Virgin 2]

I need to double check on the work done so far but I'm pretty sure the Crankshaft position sensor is fine and the rev Counter has been checked to confirm that it doesn't send a fault of any sort to the ECU. It doesn't seem to have a Camshaft one though.

[olebrock]

Bongo Techies, I have been reading through the suggestions and think a clue could be in Bongo Virgin's statement "its fine until the cooling fans cut in 2 or 3 times or running over 2000rpm"

Cooling fans cutting in !!!
Over 2000 revs !!! (in D this means traveling over 50 mph).

My fans don't cut-in unless very hot day or stuck in traffic jam (or A/C is on) !
At 50mph the air flow through rad is cooling down the coolant !
Could this be a simple coolant temp/air bleeding problem ?
Just another one to throw in a big bigger pot.

[g8dhe]

The fan cutting in so often may be because it's idling in the garage workshop rather than out on the open road.

Its not been out on the open road!

[Bongo Virgin 2]

The fault occurs whether driving or idling under garage workshop conditions. I'm not sure if the fans cut in when driving as I can not hear them over the engine. I don't get any warning lights on the dashboard so my gut feeling at present is that it's an issue related the Advance and Retard system. As the fault has ocurred very briefly up at high revs, between gear change, as I join a motorway I think I should probably investigate that next.

I'm always rolling lots of possibles around in my head though!!

[Bongo Virgin 2]

A little update. I am now starting to work through parts myself to double check things. I have had the Air Flow meter off to test it but, despite online documents suggesting it's possible, having checked with a couple of auto electricians, it seems it's not. One of the electricians said the symptoms don't sound to be inline with the Air Flow Meter but sound much more like the Crankshaft sensor.

Consequently, I am going to check the new price of this sensor incase it is cheap enough to fit one to try. On this point, I have yet to try to find it on my V6 but before I look does anyone already know exactly where it is?

If I turn up blanks on the next few parts then it needs back to back testing, ECU swapping, so it will be off to Bath!.

Thanks.

[Bongo Virgin 2]

Whoop de Whoop!! A very early start to nurse my Bongo to Bath and Bell Hill Garage. By 5pm I'm driving it back home and, trying not to speak too soon, all working properly. The Crankshaft Position Sensor and a faulty VSS wire appear to have been to blame. Tested for about 40 miles by Tom and his guys and then I drove home to the New Forest and no repeat yet. HDM in Ringwood had narrowed it down but Bell Hill put it all together again.

Thanks to anyone and everyone who has offered advice on this one and especially to the people who suggested Bell Hill. We can now plan out Summer excursion to the continent.

Hopefully, I shan't be posting anything about this fault again!!