Car Back Together -- Some Final Issues / Questions

[ScoobySteve]

I recently did the top-end + water pump + belts + WYAIT under the intake + cap / rotor / wires service.

I had a major issue with my OPRV (it sheared) that I got resolved last night and everything was put back together.

It started on the first try without problems and settled into a normal idle. There was some extra vibration but the car was on a lift (off the ground) so I think that makes any idle shake a lot more apparent. A couple things I have some lingering questions:

Belt Whine -- At first it was really bad. With the timing covers off it didn't sound right at all. We fooled around with the cam and balance belts for 1.5 hours and couldn't completely eliminate the whine. As it is...there's a little whine apparent from outside the car with the hood shut. We checked and nothing was rubbing anywhere. Ultimately, the balance shaft is pretty loose and we have the cam belt set with the 90 degree method. We tried using the Krikit but were unable to get consistent readings. We get 40, 30, then 50. At this point, I think it's at least in the ballpark.

Temperature Gauge -- My car no longer vacillates between the 1st and 2nd marks when idling and driving slowly. Now it warms up to the first mark and doesn't go higher. The only problem is that is goes lower while driving on the freeway on a cool night (high 50s). It dropped to between the bottom and first mark.

Detonation -- This problem was happening before all this but seems a little worse now. The engine runs very smoothly but under high load (5th gear on the freeway) it will experience detonation with anything more than 33% throttle. I have a circa 2002 FR Wilk chip in there. I run CA 91 gas. FPR is new.

[Slam]

Congrats on getting the car done! The belt whine may have more to do with the position of the balance belt idler. You're right in that the belt should actually be fairly loose, but that idler contributes a lot to the whine. The belt shouldn't be spinning it at all times. When revs increase and decrease the idler helps deflect some of the slack - if you watch it in action it's kinda fascinating. Try playing with and see what difference that makes. New belts will whine, too. I use the krikit and average seven readings to get a figure.

Seems your temps are now close to where they should be, odd as that sounds. So many of us are used to 944s that run hot and worry about anything lower than halfway on the gauge. After I did the head and swapped the rad on my 944 the temp gauge almost never gets up to halfway. My 924 gauge behaves the way you're describing yours.

Detonation I don't really have ideas about. Have you swapped in a DME without the chip? Do you have vacuum leaks? Maybe the Hall sensor isn't hearing the pinging.

[HondaDustR]

In my experience, the smooth idler roller for the balance shaft is a big source of whining and is really tricky to get adjusted just right. It must be something like between 0 and 0.2 mm away from the belt at rest, but this must be measured from the highest point on a tooth aligned perpendicular to the roller. If it intrudes into the belt line at all, it whines like crazy. The other trick is it kind of has to work together with the sweet spot of the belt tension. Too tight and the belt itself will whine and too loose, and the belt will slap around enough to really rub on the roller and whine. The roller is basicly there to stabilize the belt, and if the belt slaps too much, it whines against the roller. The other tricky thing is it all changes as the engine warms up, but I've had a couple cases of marginal whine that quieted down as the engine warmed up.

Originally Posted by Slam

Detonation I don't really have ideas about. Have you swapped in a DME without the chip? Do you have vacuum leaks? Maybe the Hall sensor isn't hearing the pinging.

There is nothing on the NA DME system that can detect pinging. Only on the turbos and the 16 valve motors (S, S2, 968). Is the throttle body and J-boot oily? This would mean a vacuum leak in the crankcase seals somewhere (AOS, dipstick, oil fill cap, rear balance shaft housing seals), that, in addition to being a vacuum leak, usually carries oil mist into the intake, which reduces the effective octane rating of the fuel. Otherwise, maybe it's clogged injectors, weak fuel pump, or some other vacuum leak. The AFM could also be dirty. http://www.the944.com/afm.htm ...or maybe you left something inside the motor and its rattling around whenever you give it gas.

[ScoobySteve]

Originally Posted by HondaDustR

There is nothing on the NA DME system that can detect pinging. Only on the turbos and the 16 valve motors (S, S2, 968). Is the throttle body and J-boot oily? This would mean a vacuum leak in the crankcase seals somewhere (AOS, dipstick, oil fill cap, rear balance shaft housing seals), that, in addition to being a vacuum leak, usually carries oil mist into the intake, which reduces the effective octane rating of the fuel. Otherwise, maybe it's clogged injectors, weak fuel pump, or some other vacuum leak. The AFM could also be dirty. Air Flow Meter (AFM) - from "The 944 Motronic DME" by FR Wilk ...or maybe you left something inside the motor and its rattling around whenever you give it gas.

I replaced the AOS seals though my intake was perfectly clean. Also, vacuum lines were replaced with the Lindsey kit. My idle is a little high (~1000RPM warm) but it was that way before any of this and I think it might just be misadjusted.

I was thinking of having the injectors sent out. Fuel pump is newer used (blue pump). But, I was thinking if it were a flow issue it wouldn't do it at lower RPMs in 5th gear -- it would do it at higher RPMs where horsepower is higher and fuel flow requirements would be higher.

With the FR Wilk chips there is a jumper so I might change that back to stock and see if it makes a difference.

[ScoobySteve]

UPDATE:

My car has been running very well lately (knock on passenger wood footwell). It's hot so I decided to revisit the detonation I was getting with the FR Wilk chip. I plugged the "jumper" back into the atmospheric pressure plug on the ECU and went for a drive. Detonation is gone!

I've done three things since I last tried it:

1. Belts were retensioned by mechanic to post-break-in specs. Mechanic noticed timing belt was loose.

2. Ran through a tank of Lucas Injector Cleaner

3. Per mechanic's advice, waited until the oil was warm and drove the car hard for 1 hour -- high RPM and high-load scenarios while using the tank of gas with injector cleaner.

I asked my mechanic about sending out the injectors for cleaning and he said he thinks in most cases it's a waste of money -- injector cleaner + hard driving every six months will keep them clean on the Motronic cars.

I guess my injectors must have been dirty. As I said, I've noticed the car running generally better (more power and the motor just seems happier) and that's what prompted me to go back to the FR Wilk chip and try it again.