Engine: 850 T5/R Engine stuttering at low rpm in 1st, 2nd and 3rd gear

[Clark]

Hey all,

An interesting conundrum I have at the moment for my 1996 Manual 850R saloon. I will try being succinct. I recently had some work done on the car. It needed some TLC:

- Full service
- Cambelt change (inc. tensioners and pulleys for both the Aux and Timing belt, new water pump as I am almost at 200k)
- Air con unit had a leak so that is being refurbed
- Vaccum Control Solenoid was detached (I was told) so that was repaired and re-connected
- Some vacuum lines were replaced as they had cracked
- Coolant system was flushed and replenished
- Distributor cap was cleaned

However, now when I am driving, at low rpm (in 1st, 2nd or 3rd gear) when the engine is warm, my car (sometimes) shudders as if I am in the wrong gear or as if it is being starved or fuel/air. It has been re-checked and all spark plug connections seem to be good, and the spark plugs have been changed to racing plugs (for some reason the mechanic thought it may make a difference). There are no issues when idling, only so when I lift off in 1st, 2nd or 3rd gear at low rpm, then once I am at higher rpm nothing happens.

I have been asked to keep driving it to see if it goes away, due to the work being done being quite comprehensive - I don't buy this frankly. I have been wondering...

- as the vacuum solenoid is now re-attached, maybe it was detached in the first place to work around this fault, hence it has re-appeared? My mechanic says now the car is re-learning how to perform - I don't buy this.
- could the work done now have created a fault on the MAF? The garage did run a system check and no faults were found - I presume a MAF fault would have been observed?

Any help/guidance would be appreciated as I think I need to start advising the garage. They seem clueless. Thanks in advance.

[volvo again]

As you've just had the timing belt changed the first thing I would check is that all the timing marks are spot on, maybe 1 or 2 teeth out

[Distendo]

Had a similar issue myself.
In addition to the other stuff you're doing, you could consider checking:
# the air idle control valve (remove & flush with carb cleaner)
# fuel filter (clean/replace)

[Luxobarge]

Originally Posted by Clark

the spark plugs have been changed to racing plugs (for some reason the mechanic thought it may make a difference).

They seem clueless......

Racing plugs? RACING PLUGS? What the.....??

There's no such thing. The right plugs are the right plugs, fiddling around with the spec of them, whether allegedly "racing" or not, is going to cloud the issue at best, and at worst introduce new faults. If it were me this would inspire NO confidence whatever in your "mechanic".

They do seem indeed "clueless".

If you're not experienced or confident to work on it yourself I'd get it to someone decent, who can check it over, including the timing as posted above, and look for vacuum leaks and other faults that may have been introduced by this mechanic.

[DaveNP]

I have similar problem at the moment with mine (2.4 NA rather than turbo), it got a lot worse when the vacuum pipe to the end of the inlet manifold split and seemed to get better when I did the PCV system, and replaced that pipe, but it's back again, I've yet to go over all of the vacuum pipes again to check for leaks. Similar to Clark it's OK when at tickover and even when revving without load which makes it hard to replicate with the bonnet up.

[Shinsplintz 101]

Hello Clarke - it sounds like a misfire under load. Change the plugs, leads, dizzy and rotor at the same time, all OEM. They've covered 60k now and as its an R spoil it 😀 Aftermarket ****e should be avoided at all cost.

+1 on the timing - get it checked.

I'm afraid your mechanic sounds like a big of a bull**** merchant. Find another would be my advice.

Good luck, hope you get it sorted, one of my favorites that car.

Cheers

Morgan

[Clark]

Originally Posted by Shinsplintz 101

Hello Clarke - it sounds like a misfire under load. Change the plugs, leads, dizzy and rotor at the same time, all OEM. They've covered 60k now and as its an R spoil it 😀 Aftermarket ****e should be avoided at all cost.

+1 on the timing - get it checked.

I'm afraid your mechanic sounds like a big of a bull**** merchant. Find another would be my advice.

Good luck, hope you get it sorted, one of my favorites that car.

Cheers

Morgan

Good to hear back from you Morgan and thanks for your guidance. How's your red estate coming along? Yeah I can't picture myself parting with Harvey anytime soon - thanks for making her roadworthy.

[Shinsplintz 101]

The R was put back to standard and sold on to a very nice young fella from Reading who is currently lavishing the old swede with some love - and running it as his daily - so pleasing result all around.

I've got a couple of T5s to sort ( one to keep & one tomove on) and then with a bit of luck I might finally get in some time with my R saloon that is long overdue a bit TLC!!

Don't give up hope with yours, it'll end up being something relatively simple, but do try and stick with OEM parts and see if you can find a spanner man who has a passing familiarity with pre 2000 turbo charged cars ( ideally volvos).

All the best, Morgan

[cyclogenesis]

I would check for induction leaks first. These engines seem to throw wobblies when there is a loose hose or pipe.