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156 Power Loss at Higher Revs

3K views 14 replies 12 participants last post by  lkomnino 
#1 ·
Since the timing belt was replaced last month, my 156 1.8TS has had no urge above around 3800rpm. The garage who fitted it say that the timing is spot-on and that maybe it needs new plugs. It seems to accelerate fine to 3800, but above that it's absolutely dead. Am I right in thinking that power would be down across the rev range if plugs were the problem?

Steve
 
#2 ·
probably.

The plugs would exhibit other symptoms too like misfiring, hard to start maybe.

If the car ran fine until they replaced the timing belt then they have done something wrong.

One possibility (although i think the belt is wrong, even one tooth out will affect the timing) is that the crank sensor is failing at high rpms or the fuel pressure is tailing off at that point? (maf etc)

If it did run ok before the timing belt, and it didnt break but was replaced as a service then I would insist the garage fix it or take it to another place or the RAC for an independent report, then take it back to get it fixed if they are wrong. Sounds the most likely thing that they have the belt on slightly wrong. Are the revs limited too at less than the original limit?
 
#4 · (Edited)
I would bet that they did not use the correct timing blocks when they fitted the belt. Incorrect cam timing can cause the symptoms you describe.

When they say they got the timing "Spot on" how did they check it?

This is a common issue, my 156 drove ok when I bought it, but I did a routine cam belt change as I wasn't sure when it was last changed. The cam timing was quite a way out, and the car now has far more "Bite" at the top end.

The other possible cause is a Faulty MAF sensor.
 
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#5 ·
It's too much of a coincidence that you lose power just after they did the cambelt. Either they've left something disconnected, or a cam is out by a tooth - it will indeed make all the difference (had this previously on a Lancia Dedra 1.8 - transformed the car when it was put right).
 
#8 ·
Thanks, all. Very helpful. To answer some of the questions:
1) When stationary, the revs will go beyond 6000 so I think they will reach the original limit.
2) It wasn't an Alfa specialist who did the belt although one of the engineers is Alfa trained.
3) The timing was proved to be 'spot-on' by removing the valve cover and measuring the valve timing.

I suppose the next step is to try disconnecting the MAF sensor and see if it makes things worse.
 
#9 ·
Hi
I just bought a 156 2.0 ts and have the same problem, mine revs up perfectly to 4k and hesitates up to 6k. Stationary it also revs clean all the way up. There's no misfire and the engine sounds smooth when driving. It does idle un-even also at times this I think could be the idleing actuator. Any advise would be great!

RaZ
 
#10 ·
Could be a problem with the variator that controls the variable timing of the engine. The problem you describe is typical of this fault. The functioning of the variator can be tested by your garage provided it has a dedicated alfa test computer. The test is simple and takes minutes. Your problem is not spark plugs. My alfa was purchased with 90000 miles on the clock with the original plugs showing no fatigue.
 
#12 ·
Have noticed the same on my 1.8 ts cf2, I changed the belt with cam blocks and drives fine otherwise. I thought it might be injectors as was sitting a while, maybe even fuel starvation. Pulls well midrange, but 4k up it is 'strangled'. No errors showing. Passed MOT today, so emissions fine. Will be giving it a dose of oil flush before a change, and plugs. But obviously when I disconnected maf idle dropped and hunted. Puzzling one.:-?
 
#13 ·
Agree that the sparks are an unlikely cause but on most 4 pots you'd possible change them anyway just to be sure. In the Ts this is obviously a little more costly.
I recently read an interesting thread about a mechanism in the Ts that raises the idle speed while the car is in motion. The mechanism can be circumvented by messing around with the wiring around the speedo. Sorry to be so vague but a search might be useful. It was a weird one and definitely an Alfa thing!
 
#14 ·
Got replacement maf element and all is cured. Did plugs air and oil filters and oil as needed it anyway. Didn't realise that there are 3 different pollen filters for the 156. Have the double type for jts, but got a big single for 1.8ts and was a few inches too big. Has anyone has heating that goes super hot then cold? Cleaned interior thermostat but mini fan behind it might be buggered. Yeah hot and cold sweats. :-&

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#15 ·
Well still seems a bit slow on pickup, in comparison to jts. Have to keep over 3.5-4k to keep in power band. Maybe I have got timing out one tooth? Any easy ways to check. was thinking lobe locks and crank marker, but maybe an alfanista could advise...

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