Juandotto

Hello all!!!

Actually my 1986 Euro 928 S2 is at the workshop. The mechanic have done some many repairs on it due to low performance, being the main problem a rich mix causing engine jerks and misfires.

In the last few weeks,he has changed the fuel regulators and the fuel damper, delcos, coils, the belt of the twin dizzy and have inspected that the engine have no air leaks. The MAF has a sticker with the date of a refresh done in 2016.

He called me this morning to say that the car runs great and strong, but at low rpm the car feels so heavy…. there is something wrong that we don’t know and he think that using a clean inyector or similar, the car will be ok in a few trips.

He think that the cause of this mistake is due to a rich mix during some many years, and the engine is full of cinder and must be cleaned along the next kilometers (currently has 95.000 km).

I have told that maybe must put a new temperature sensor, but I have decided to share with you this problem.

Any help will be appreciated.

Best regards!!

Otto

Juandotto

This is my euro manual 86 S2

Darklands

The S2 hasn‘t the torque of a S4 at the bottom end but at 3.000 rpm she should wake up.
I can told you that my S2 purchased 6 month ago runs every week a little bit better. Every turn to Hamburg she must run 30 km between 200 and 250 km/h on Autobahn.
My wife lives there and I in small village 80 km away.
So the assumption of your mechanic about the injectors should be true.
This cars are build to be driven, put your wife and luggage in the car and visit Paris or another city for a weekend.

Juandotto

Very interesting your feedback about your S2. Now, I’m in calm knowing that the car could be so much better along the kilometers.

I remember that my previous 89’ S4 with automatic transmission feels heavy too, because the weight was about 150 kg plus than the S2 and the automatic transmission don’t help to have a fulgurant aceleration.

Many thanks Karsten!!

Otto

8cyl

I think it depends on how heavy feeling we are talking about relative to everything else. My Euro S1 feels quick to get moving even at the lowest rpms. If your mechanic thinks it feels unusually heavy and slow compared to others he has driven and worked on then it is worth investigating.

davek9

Running an overly Rich mixture for any period of time requires new spark plugs.
If it were my car, I'd replace all spark plugs (numbering them as thy come out) and doing a compression test and documenting each cyl to asses the over all mechanical condition of the engine.

Let us know what you find.

Thank you,

Dave K

ROG100

Replace the injectors - Made a big difference on my 85 & 86 S2.

Juandotto

Thank you Davek9.

Forgot to mention that my mechanic replaced the spark plug too at the same time.

There will be another problem.

Regards

Otto

Juandotto

Hello Rog100..,, yes, there will be a big difference with new injectors… the improve could be “biblical”…

But, at the moment, due to the cost of new injectors, I prefer to investigate another causes…until the root of the problem…because the car runs great, except at low rpm.

Many Thanks !!!

76FJ55

Have you verified cam timing? Doing as Devek9 suggests and getting compression numbers on each cylinder may help diagnostics even if you've already replaced the plugs, it may be worth pulling them back out for compression testing..

Speedtoys

The root of the problem could be your mechanic comparing this to a low geared US stop light redneck racer.

This isn't that car.

All in all, theres nothing to diagnose with "he thinks its slow".

Got a local dyno??

hernanca

^^^^^ Very Possibly.

What other cars are you (or your mechanic) driving? It could simply be perception, although checking timing and compression would help eliminate any underlying problems and also provide you some good baseline information.

When I had two different 928's (A=86.5 Automatic with 6.5L stroker motor; B=86.5 5-speed), I drove "A" more frequently. The first time I did this and then switched to "B", I thought "B" had a problem at first. After a while I realized I had just become accustomed to (spoiled by) the more powerful motor.

Darklands

The cars drive all slightly different!
My 84 S feels more agil in the mid rpm, maybe this comes from the lower weight or the more restrictive early dual exhaust.
The 86 has more power at high rpm, it’s amazing how fast this car is at 160 mph.

If you look at your spark plugs you can see if the car has an equal burning of the fuel.

I have 10.000 € of parts in the 86 one in the last half year, I think this week I will do the water bridge and the new injectors.

Petza914

Auto or manual trans? If an Auto, what years does the transmission start in 2nd gear instead of first as that could certainly make it feel sluggish when leaving a stop. There is a kickdown mod where you can wire the thumb button to the kickdown switch and if you hold that button when leaving a stop, it will start in 1st.

My 84 Euro S 4-speed starts in 1st anyway, but I think they changed that at some point.

76FJ55

Second gear start began in 87, so should not be an issue on ans S2s.