[jimbob123]

Hi, Have a 52 Reg 1.8 16V auto Renault Laguna with a fault.

The car will sometimes (almost everyday) come up with a Fuel Injection and Gearbox fault error. When this happens the car will rev between 2000 & 2200 RPM and the accelerator pedal has no control at all. The car always restarts after being turned off, sometimes straight away and other times needing anything upto 25 minutes before it will start again without the fault reoccurring. It also sometimes struggle to idle when starting and sits at about 500RPM before stalling itself.

When the car is running there are no obvious problems at all until the message appears and it needs to be stopped and turned off. The problem although not always often occurs when pulling away after being stuck in traffic for a few minutes.

The fault codes dont often appear at all but the ones that come up are P0700 refering to transmission control system malfunction and others that relate to an unknown misfire.

Spark Plugs and coils replaced but no change. Any help would be much appreciated.

Thanks, James

 

[chris m]

The revs are limited by the engine management system when faults are detected (Limp mode) to prevent engine damage. Does the auto light come on at other times, could be low in ATF, trouble is there are so many sensors the codes would have to be read to be sure but the hydraulic distributer is a popular one. Not sure re the injection problem try the Laguna articles (link on side bar) or a forum search as I think this has come up before so there may be a solution posted

 

[jimbob123]

Most of the time when reading the fault codes there is none there. Thats the strange thing it doesn't go into limp mode it just stays at about 2000RPM and will not go down. Thanks for your reply.

 

[mlg73]

Hey Guys

I got a 52 plate 1.8 Laguna auto with an identical problem, auto box light and engine management light comes on, car slams into 3rd gear, when its put into park it revs between 2000 & 2200 rpm. A sure sign the fault is comming is when the car starts stalling and running rough (no warning lights on). often locking the car and un locking it clears the fault, but sometimes disconecting the battery for 2 minutes is required. no fault codes show up, I am out of ideas now!! help !!

 

[mord]

mlg73
have you tried checking all earth connections to the engine, gearbox, chassis and battery ?

 

[mlg73]

well, checked all conections, earths, multiplugs etc, noticed that I only have a 360 amp battery on the car (not sure thats enough for an auto) cleaned the breather on the autobox. when I ran the car without the air box, it ran really smooth, when I re conected the air box and started the car, it stalled and ran eratic (no autobox light or engine management light) I removed the air filter and it was real dirty, I gave it a good clean, re fitted the air box and now the car runs like a dream!! cant see how that would cause and autobox fault :-( unless it was causing the engine revs to drop to low, thus affecting the ampage to the autobox sensers?

 

[mord]

buy a new air filter (unless its a metal K&N one)
the battery should be the bigger one available, as you have the automatic gearbox.

and give the car a good run(20min+), the battery voltage is proboably low, due to too many short trips not charging the battery up enough.

 

[bigbountyhunter]

Hi Guys,
I have had the same old Laguna problems as you are all experiencing, limp mode, warning lights eratic revving etc etc,
I had my Lag linked up to a computer which said the fault was the "throttle body" that was cleaned and put back in car was fine for about two hours then back into limp mode and eratic revs. that cost £160 for the diagnostic, the throttle body cleaned and labour, I then changed the throttle position sensor myself at a cost of £100 for the complete unit from renault main dealer this did not work either , the ecu was taken out and it was noted that some bright spark designed the ecu to sit under the battery this causes problems with damp and corrosion, this was taken out cleaned and put back to no avail, along with other bits and bobs we had tried like air flow, coils, spark plugs etc etc, nothing has worked, this car has cost me too much money now and is still running awful.
Such a shame and such a common fault with these cars, its a beautiful car to look at and when it drives right its a lovely car with plenty of grunt, its just a shame that in my opinion it has been over engineered to the point where even a diagnostic computer scratches its head! :d.
Like many of you ive found Renault pretty unhelpful, and im afraid my solution to the problem? i sold the car this morning as a spares or repair lumpy runner