440 1.8i fuel consumption down, running rough

[twomo]

Originally Posted by Darlo 1

Try having an emissions test done could be your cat is begining to break up.

This did fleetingly cross my mind Darlo, as i've had every bit of the exhaust replaced in the last 3 years, except for the cat of course. I'm sure it wouldn't be worth the outlay, relative to the value of the car, but thanks for the tip all the same - i've added it to the list of things to get checked! twomo

[B20F]

The cat wouldn,t cause a high fuel consumption. If it goes bad it would only influence emmision. Most of the times it got blocked and that makes the car loose power in the higher refs.
Best is to first check the lambda. It's a pity the ecm doesn't work in socket#2But that happens more often as it's an old system.

[grass hopper]

just a thought, start the engine and try testing the codes again in socket 2,sometimes if the imobiliser is on it can do this.

[twomo]

Hi, just tried the ECM reading again and got a reaction this time on socket 2 - it's given a 4-1-1 reading ("Throttle switch signal faulty or missing"). What d'you reckon? Would this explain all the symptoms i've been describing? Thanks...

[carl4u44]

Worth replacing that sensor or checking the connection to it etc. Dont forget to erase the codes either by unplugging the battery or holding in the diagnostic button method.

[twomo]

B20F - thanks for your reassuring words on the CAT! All i can tell you about the lambda is that when the car was MOT'd early Oct 09, it passed with a reading of 1.012

Grass hopper - think you were right about the immobiliser. Turning it off has produced the results from socket 2 - a great tip for others.

I just went for a spin and thought i'd give it another go on return. So, in addition to the (cold) 4-1-1 reading as above, i've now got (warm) readings of: 1-2-1 (Air pressure sensor, no signal correspondence); 2-2-3 (Idle speed regulating valve: no/faulty signal); and 3-1-3 (Charcoal absorption canister valve: signal faulty).

I've now spoken to my garage man Don, who says the warm readings (except for 3-1-3) probably all result from the 4-1-1 problem, which is probably all related to the same problem I had last year, which was sorted by replacing the stepper motor.

I'm taking the 440 in to Don next Monday, but your thoughts are most welcome before then - with thanks in advance...

twomo

[Multiplex]

You mentioned the two hoses at the rear of the manifold earlier in the thread - i would start first by having a look at these. One of the hoses is connected to the manifold pressure sensor and could be giving you both the the mainfold pressure DTC and also account for the reduced mpg.

Look down the rear of the engine for two black plastic hoses. Pull them off and have a look inside. One of them (the one to the manifold pressure sensor) should have a restrictor inside. Push it out and make sure its not blocked.

Have you tried erasing the codes and doing a re-read after a run?

Some of the codes could have been left there since earlier repairs.

[twomo]

Thanks for your suggestion Muliplex, but things have moved on a bit now.

Garage man Don (proud owner of a V40 1.9D, by the way) first found a crack in the dis cap, so that was replaced. Same time, he found the corresponding spark plug was shorted, so the car's been running on 3 cylinders, hence the fuel problem and everything else.

Also, he traced back to the inlet manifold and of course spotted that the gasket needed replacing. That was Monday.

Today (Wednesday) he did the manifold gasket, and was very happy with the results. When i arrived to pick it up, not so happy. He had taken it out for a spin and discovered that when reaching about 1500 revs (2nd gear), it started to do that thing of losing power then suddenly surging forward.

This was confirmed when i drove it home, with a lot of power drops and kangarooing on the way. Now, Don reckoned it was the stepper motor again, like the original problem last summer (he fitted the new one in July 09).

But, the service guy at Braydon Motors disagreed, suggesting a problem with the charcoal filter/evap canister system. This was one of the fault codes that came up recently (3-1-3). I've read that the hoses on these are prone to cracking, and as far as i know nothing has ever been done to this on my '96 model, which has now done nearly 86k miles. Sound likely?

Having said that, i did the diagnostics again after getting back (just - it cut out and died as i was approaching my road) and the only reading was a 4-1-1 on socket 2, as before, which is "Throttle valve signal faulty or missing". This would appear to support the stepper motor theory.

Now i've found out what the Evap Canister is and where, i'll be calling Braydon Motors back in the morning for further discussions, but would very much welcome any feedback from this as well. Not a job i'll be able to do myself, so i'll need to get back to Don, but i really need to find out what exactly this new problem is, and quickly!

Currently i feel like kangarooing down to B&Q to get a large sledgehammer and chainsaw...

[B20F]

You can take the evap cannister out of the system by taking the small black hose from the cannisiter to the inletmanifold off and plug off the connection on the manifold. To plug it off use the attached hose, cut off 2-3" and put a small bolt with the right diameter in the open end. There's a valve on the cannister that can go bad and give the faultcode 313. This will make the manifold to draw false air and can cause bad idling/kangarooing.

[twomo]

Great, very interesting thanks B20F. This has the sound of a temporary fix to give me time to get the canister sorted/replaced - am i right, or can i drive around indefinitely like this?

Took it out for a necessary spin this morning. The problem seems to be worst when in 1st & 2nd gears. If I keep the revs much higher than normal, it seems to force through the problem a bit, and it goes a bit better in 3rd/4th. The way it is though, i feel i shouldn't be driving it.