Last chance saloon

[7 Seat Sports Car]

Hi all,

My ME7 V70 T5 is running rich all the time and I'm looking for some advice on what else I can check as it's going to fail it's MOT on emissions and if so it's getting crushed! I'm at my wits end.

I've gone through Vida and looked at resistance and voltage figures for both O², MAF, ECT, IAT, MAP, PTC TCV and evap purge. I cannot find anything wrong or out of spec. I've had all the induction pipes and intercooler as well as intake manifold and throttle body off and checked for leaks, nothing. I've double checked all the vacuum hoses, again, fine. I've had the exhaust off and found a few pinholes in the work experience welds on the aftermarket replacement Cat which I've gummed up but that had no effect. Not taken exhaust manifold or turbo off though.

At idle I'm reading approx 14kg/hr maf, 2ms injector pulse time, 6° btdc ignition angle (hunts about a little but generally there). All temp sensors agree when stone cold. I've done the Vida thermostat test and it's good. Will climb to 105 then fans bring it down to high 80s. I'm getting 0.8-0.9V on rear O². From front O² I get a random selection of either ECM-280A faulty signal or ECM-2810 faulty signal. Both O² sensors were new 2 years ago with the new cat. I've put 2 other new ones in and codes come back instantly. If I disconnect rear O² the car doesn't always throw a code for the front sensor and drops into closed loop when short term fuel trim climbs to +25%! Long term gets as far as +15% then stops. If I disconnect all sensors except maf it stills runs rich. I have a cloned ECU and it's exactly the same with that one too.

5 new coil packs put on and plugs are 8-9k old and gaps are good. All new stuff is Bosch by the way. This includes my replacement maf and O²s. Also replaced fuel pressure regulator, fuel pump and injectors.

I've had the engine bay loom out of its conduit and checked all wiring for damage, none that I can see. No shorts to anywhere or open circuits on anything to send from the ECU box connector.

Cylinder compression seems ok, warmed up dry/wet figures are 165/195, 160/180, 150/170, 160/180, 160/180. Is cylinder 3 too low in comparison or passable because it's at least 150?

Pulling 15 to 16 inHg from intake manifold brake booster port but it takes a while to get this high, starts around 13/14. Needle fluctuates ½"Hg at slow and steady rate.

Car has 239k on it. Is it time to say goodbye? Or does anyone have any other ideas that don't involve throwing more money at it. I'm happy to spend time testing and if I find a hard fault I'll pay to fix it but won't spend on a whim.

Thanks in advance.

Drew

[Luxobarge]

Bit of a basic silly question, but how do you know it's running rich? What exact symptoms do you have?

[SteveSarre]

Hi Drew

You have certainly done a lot.

Did the engine run OK with new O2 sensors etc when you first had the new cat fitted?

Have you asked Volvo for a part number for the front O2 sensor (for your VIN)? Was the original made by Bosch? (To double check the suitability of the Bosch parts that you have fitted).

If you have had the ECU remapped and an after-market cat fitted, I don't know if that would change the O2 sensor requirement.

Did the problem come on suddenly or gradually?

Did the onset coincide with any other work or changes?

Certainly the front O2 sensor codes seem like a main suspect.

Hope that helps,
Steve

PS
Also can you get a Volvo part number for the MAF for your VIN?

[Tannaton]

This is one of the few time where I don't know what to say - you have checked everything and more, it would seem.

If it were my car I would try and borrow or get access to a car with the same engine so you can compare readings of sensors and actuations side by side.

I was going to say don't trust a part just because it is new but then read you bought all new Bosch, which is hard to argue against as a strategy.

[7 Seat Sports Car]

I used to get around 400 miles per tank of fuel then that dropped to 300-350 tops. Plugs are sooty, O² sensors are sooty, the end of the tail pipe is sooty, the exhaust smells acrid and when in closed loop the fuel trims zoom off to the max and rear O² reads 0.8-0.9V. I'd like to think I'm not barking up the wrong tree here and all the symptoms are for running rich or somehow detecting false lean and over compensating.


The car ran sweet before the cat was fitted (old one was nicked) then I was plagued with a cat efficiency code ever since. After a year of this I got fed up and started to look at what I could do as I thought "it's a new cat, it can't be wrong". A rear sensor spacer didn't work so I went to remove it and that's when I suddenly started to get front O² codes! I'd get P0134 sometimes and P0135 most of the time. Battery was disconnected every time I swapped sensors. Randomly the ECU will not find any fault and go closed loop and hoof fuel in like no tomorrow.

The Bosch sensor part number is etched alongside the correct Volvo part number according to Vida, my vin says it's MY99. MAF is a part number match with the one that was factory fitted. And Bosch. After I replaced both newish O² sensors with other new ones it didn't change anything. Either I've bought duds from autodoc or it's not that.

ECU is a clone of my existing original ECU but immobilizer is switched off, not remapped. Is it likely the programming is corrupt and I've copied this fault to the clone.


If it's electrical I feel I should be able to prove it one way or another. If it's mechanical e.g. engine health then how do I isolate this as the problem without lobbiing money at it.

Incidentally, I've got a block tester for identifying bad head gaskets, no gas gets up to the reservoir and the pump on it cavitates as I'm using it. Fluid stays blue. Crankcase breather is only a few years old and I've just cleaned it out when I took the intake manifold off the other day.


Usability wise it starts first time, idles at solid 850 and it goes like a stabbed cat. However on occasion its lumpier than school custard and can watch rpms drop while trying to accelerate. On one occasion I managed to get my obd2 dongle on when this fault was on and the fuel trims were max negative! I'm proper lost.


Cheers, Drew

[Luxobarge]

Hmm, an interesting one. I'm always super suspicious when we're talking about an ECU that's been fiddled with. If it were me, I'd try somehow to get someone with a bog standard never touched known working ECU and try to borrow it for a day or so, at least to eliminate that area.

Otherwise, vacuum leaks are favourite for doing this sort of thing, how confident are you that there are absolutely NO vac leaks anywhere on the whole intake system?

[ITSv40]

Originally Posted by 7 Seat Sports Car

The car ran sweet before the cat was fitted (old one was nicked) then I was plagued with a cat efficiency code ever since.

Given that you have done everything else I would suspect the cat is inefficient. Was the replacement cat aftermarket or genuine Volvo.

Several years ago I had a '97 V40 2lt petrol. Every year the emissions sailed through the mot with no issues at all . Then one year it started to run rich and the cat started internally rattling - it had done c250,000miles, so decided to replace the cat with an aftermarket. Car ran ok, but when it came to mot time the emissions were way off. MOT tester had to run the engine at full power for an inordinate amount of time to get the emissions to pass. The pistons were screaming up the bores, the block must have been red hot and at the point of boiling the oil! The tester who knew the car from previous tests declared - 'that was not good'. I decided there and then I needed a better quality cat. Sourced a secondhand genuine cat and next mot test it sailed through the test as normal. Tester remarked: 'I see you have got rid of that cheap cat, they are never any good'.

[7 Seat Sports Car]

The fault presented itself with the original ECU. I only got a clone in an attempt to isolate the fault with a view to remap that one if I could cure this other issue.

I've had all the induction pipes off including the intercooler, taped off one end and blown down them to pressurise them. Very Heath Robinson I know but it served a purpose and the only air leak was from the intercooler weep vent until I blocked that off as well. All the vac lines are replacement silicone ones and also leak free.

Think I may try and remove turbo and exhaust manifold next. It's the only thing I've not taken off as it seemed the most implausible as there are no exhaust smells when cold.


With an ECU fitted after a power cut i.e. no adaptations yet, it drops into closed loop without fault codes and trims to max positive and after some time like this starts to throw codes out and stays rich and open loop. Both ECUs, original and cloned, exhibit the same behaviour.

[7 Seat Sports Car]

Originally Posted by ITSv40

Given that you have done everything else I would suspect the cat is inefficient. Was the replacement cat aftermarket or genuine Volvo.

Had to be aftermarket as Volvo no longer sell genuine. They didn't even have the front O² sensor available anymore, just the rear for approximately 1 million dollars.

Considering the number of T5s that are still out there I'm betting that any that come up for breaking get the cat weighed in straight away as they're worth a fair chunk of cash so chances of finding one are slimmer than an anorexic tapeworm. And even then no guarantee they're not knacked as they'll all have space shuttle mileage on them.

[SteveSarre]

Hi Drew

Just to be clear. You say the car is "running rich all the time" . So it is not an intermittent fault, and it runs rich at all throttle positions and loads?

You say you have replaced the fuel pressure regulator. What fuel pressure is present at the rail?

In other posts, you have mentioned fitting a new ETM. Was it programmed as necessary (I believe the only options are "turbo" and "non turbo", but I don't remember what new ETMs are set to when they come "off-the shelf"). Is it possible to use VIDA to interrogate to check that the current ETM software is correct for your T5?

Steve