slow to rev

[3stewartS]

I am in need of advise. 87 911 3.2l stock engine is slow to rev and really lacks power. Symptom appeared after engine drop to repair transmission leak. The car starts easy and idles smooth but when you snap the throttle is revs very slowly. (as if the ignition timing was very retarded). No work was done to the engine aside from basic maintenance type of things, valve adjust, plugs, cap and rotor and I have verified those things. I did pressure wash the motor while is was out but I don't believe that had an affect.
I did also verify idle switch and wot switch are working.
Ideas?

[3stewartS]

My concern/symptom is a bit hard to describe. The engine simply does not rev quickly. not like a misfire or even like a plugged exhaust, alot like the ignition timing was 20 or 30 degrees off. I did throw a timing light on it and it falls in the middle between what I believe to be Z1 and 30 deg BTDC. (no real marks on pulley)
The idle is smooth at or near 900 rpm and after warm the car is drivable (but my 6 cyl F-150 would run circles around it). It will rev to the red line but it takes a second or two to get there (even in neutral)

One more symptom, while driving under load the gas pedal vibrates hard, I think I may have bent the linkage. It is hard for this old man to lay on the concrete so I haven't got back under the to check.

So over the past couple days and many searches I have still come up empty. I have re-checked all the electrical and vacuum connection that I can find as well and ground connections. May have missed something but for now I am confident I reconnected everything correctly.

As I understand it the ignition timing is not adjustable on this 3.2l.
I assume the 2 reference sensors are pulse generator (vr) type sensors with 1 counting RPM (crankshaft position) and the other used for CID (camshaft position).
If the 2nd one used for CID were bad, would the engine run?

Forgive my ignorance as this is my first DME style 911. Just when I was starting to understand CIS, I thought it was time to move up.
And all of my reference material is for pre 1984 cars. (this one is an '87)

Thanks in advance for any help/advise

[Walt Fricke]

Have someone step on the throttle (engine off) while you look under the rear decklid to see if the throttle advances to full open (90 degrees from idle stop). Easy to mess up reattaching linkage while reinstalling.

Check plug wiring. If you reverse two wires you get a 4 cylinder car. Though it is peppier than one might think - I did that at an autocross by mistake (of course it was by mistake - I'm not so good I try to handicap myself for the challenge), and my times were pretty decent considering.

The cylinder head sensor, when it goes bad, can produce confusing results. But that includes, usually, hard starting. I'd put that farther dow3n on the list.

[Noah930]

My car was "slow to rev" once at an autocross. Turns out that the plastic gas pedal was disconnected from the metal rod which it actuates. When I had taken the floor mats out beforehand while prepping the car, I must have dislodged the pedal from the rod, and the rod was randomly sticking into the plastic "waffles" on the back of the pedal, resulting in a really sluggish and anemic motor. If not that, I'd agree with your plan for checking the rest of the linkage from pedal to motor to make sure something simple isn't causing any hang-up.

[3stewartS]

Thanks Noah, the vibration in the pedal is anecdotal to my concern. if I open the throttle at the throttle body, the concern is the same.
This is an engine performance problem.
Maybe air flow meter?

[scarceller]

Timing at idle in the 87 3.2L should be right near 0deg TDC. Or very slightly retarded, like -2tdc. It should not be way off the TDC mark.

Did some one remove the wires and maybe get CYL # 1 wrong? You said the timing is between the Z1 and 30 mark, this is very very wrong! Do not run this engine under any load till you figure out what's going on.

Cyl numbers as follows
Front of car
3 - 6
2 - 5
1 - 4

Firing order:
1 - 6 - 2 - 4 - 3 - 5

[3stewartS]

I did remove the plug wires (not from the cap) and I had the cap removed from the dizzy. tonight I will roll it up on TDC and make certain the rotor is pointed at #1.
I should have done this already since it makes the most sense!
As we all know when your working on cars we forget the basic simple stuff.
Thanks

[T77911S]

Originally Posted by 3stewartS

Thanks Noah, the vibration in the pedal is anecdotal to my concern. if I open the throttle at the throttle body, the concern is the same.
This is an engine performance problem.
Maybe air flow meter?

i think his point is even though you are pressing the gas pedal to the floor, it is not opening the throttle body due to linkage problems.

if i remember correctly from when we put my brothers engine back in, there was a clip that was hard to get back on the linkage on top of the motor.

[3stewartS]

I understand. and once it is running right I will make sure the throttle is opening all the way. I want all the power I can get!!!

[JJ 911SC]

Originally Posted by 3stewartS

I did remove the plug wires (not from the cap) and I had the cap removed from the dizzy. tonight I will roll it up on TDC and make certain the rotor is pointed at #1.
I should have done this already since it makes the most sense!
As we all know when your working on cars we forget the basic simple stuff.
Thanks

Originally Posted by 3stewartS

... And all of my reference material is for pre 1984 cars. (this one is an '87)

Thanks in advance for any help/advise

Did you had an SC before?

Their distributor turn CCW while an 87 turn Clock Wise. If you have done your wiring from memory which could be the problem.

[scarceller]

Or could you have had the timing light pickup on the wrong cyl spark wire?

No matter double check the firing order and be sure your starting from post #1 then clock wise

[911pcars]

How did you rule out restrictions in the exhaust system, like a clogged catalytic converter or structure failure in the muffler?

Sherwood

[3stewartS]

Sherwood,
I really didn't rule it out, just that it ran well before the engine drop and nothing would have changed in the exhaust system while it was on the jack. (at least I hope it didn't). this engine will reach 6000 rpm even under load, it just takes awhile to get there! BTW I have only 16" of vacuum at idle. someone suggested a large vacuum leak. I have looked but will look again

JJ and SCARCELLAR, I will be double checking firing order this evening!!

[scarceller]

Sherwood,

The red flag I picked up on was that he is seeing idle timing somewhere in the center between Z1 and 30deg mark. That is not correct, has to be very near 0deg on the 87 3.2L

[3stewartS]

I am now relatively certain the firing order is correct. and the rotor points at the mark on the dizzy housing with the crankshaft TDC compression stroke #1.



This picture would indicate where the timing light flashes and I am again relatively certain I am hooked to the #! plug wire.
With out literature or experience with the 3.2 (and no identifying mark) I assumed
the mark on the left is TDC and the one on the right is 30 degrees BTDC or total advance. Please correct me if I'm wrong (we all know what "assume" means right?).

The temp sensor resistance is 2.2k ohms at ambient temp 78 deg F.
Does that sound about right?



All of this information and none on this car!
When this one is done I'm going back to CIS or carbs!

Many thanks for all your help

[3stewartS]

I have forgotten the obligatory picture of the car so here it is:

[scarceller]

The mark to the left is Z1 (TDC) and the one to the right is 30deg BTDC. If your timing at idle falls in the middle it seems wrong, that's like 15BTDC and the spec is 2BTDC.

Also test the timing as soon as the engine starts up, it is possible that you have a faulty reference sensor that misses seeing the reference screw on the flywheel, if this happens the timing can start to wander off it's mark if the speed sensor then miss counts a tooth. Also during cold start the timing should go to above 10deg ATDC test that also.

The timing is controller by the chip in the DME and it can't be altered. Are you running a stock chip?

I'm sure you'll get to the bottom of the issue. If you like send me a PM with your email as I think I can help in other ways.

[scarceller]

I just went out to my 84 car and looked at my pulley it does not look like what you posted! The 3.2L pulley has a Z1 and a 5DegBTDC mark the 2 marks are very close together and they are labeled 'Z1' '5' with actual stampings. Then the pulley also has 2 more marks not labeled at the 120deg and 240deg. I can take a picture if you like.

The 3.2L pulley also has 2 belts: one for the engine Fan other for the AC compressor.

Bottom line is that pulley does not look like mine.

Find true TDC via methods in the above post to sanity check that pully.

[3stewartS]

This pulley is not like any other 911 I have had, but this is the newest air cooled 911 I have had. It does have the A/C pulley. I am sure the mark to the left in the previous picture is TDC.
I am focused on the timing as being my problem but it could easily be something else! I have a tendency to focus in on one thing and miss the real culprit!

[Quicksilver]

I'm wondering about the crank sensors. I don't think there is a way to mess up the mounting bracket so the angular position of the reference sensor was off. But I'm not sure...
Anyone have one where they can give it a good look?

Also...
Wondering if there is an issue with the connector at the back of the compartment for the injector harness. You can check the individual injectors by popping the connectors off one at a time while it is running.

If you have an IR pyrometer/thermometer you can use it to get readings on the individual exhaust ports and tell if the any of the cylinders aren't burning or not "pulling their weight".