Not hitting redline (6900 RPM's) in 1993 Q45

[Infinitiguy19]

OK I have found yet another new possible problem on my Q45. I redlined my Q45 for 1 second while the laptop Consult was hooked up. I noticed the highest RPM it reached was 6775.

While accelerating at Wide Open Throttle (WOT) it shifts at 47 MPH at 6388 RPM's D1->D2 (Not that RPM's matter in this case).

But do the the above RPM's determine the Transmission I have 90-92 or 94-96 gearing?

Also what could case the car not to redline at 6900 RPM's and instead redline at 6775 RPM's? Crank Angle Sensor (CAS), ECU?

I also read from Q45techs posts that the CAS gets worn over the years and and gets "Slowwer". thats because the seals and internals fail slowly. He also said that he has never seen a high millage Q45 that has had one replaced not gain any HP, Infact all gain at least 4 HP which is barely noticiable at seat of the pants feel.

Also to add if it makes any difference when at redline for a brief second I could feel the engine shake a lot, well enough to feel at least.

I assume that's because the Fuel and spark is being cut?
Modified by Paul Wall at 7:23 PM 9/9/2009

[qship96]

Kinda like expecting an old man to run the marathon at full tilt.....

[Q45tech]

90-93 gearing as 1st gear is ~ 1333 per 10 mph, so 4.7 x1333 =~ 6265 rpm in a 94-96 it would be ~5% less rpm. Obviously tires [brands, model, sizes and psi] create a variable [1.9% in your case].Remember maximal acceleration occurs above 4,000 and below 4,500 rpms.

The thing to observe is what is the after shift rpm in 2nd when the ignition advance returns to normal ~20 degrees ATDC.

[Infinitiguy19]

Not really because the car (body...) has 132K miles and the engine was rebuilt at 40K miles in 1997 because the first owner (I am the third owner) hydrolocked the engine. So the dealership in Florida replaced EVERY GASKET, re-ringed the pistons, flused the trans fluid and basically overhauled the engine...Yes I know your feelings on the dealership Qship but I think they did a good job. So right now the engine has 92K (I say that because they re-ringed the pistons there by kinda restoring compression).

Thanks Qtech that proves that every 90-93 Q45 has the same transmission, I am not sure about Roberts car though because he said he had the 94-96 transmission.

but do you guys think a new CAS is in order or can these be rebuit?

[qship96]

Is CAS confirmed malfunctioning? Any code for it showing?

[Infinitiguy19]

Well i wiggled the connector while running with no change.

I got a CAS code when I unplugged the MAF sensor to see if it would still run. Because before when the car idled worse than it does now it would cease to run when the MAF was unplugged.

But I also have a personal spare CAS from a engine with 137K miles.

Also Q45tech is the the O-ring that gets worn over the years that can cause problems:
Modified by Paul Wall at 8:41 PM 9/9/2009

[Q45tech]

Use a digital oscilloscope to view the 1 degree pulse at high rpms any drop outs will cause spark scatter but that won't effect power by much [say 10 HP] if really bad.

I replace mine with a brand new unit around 300,000 miles due to rough looking waveform above 6,000 rpm but I could not feel any difference with new unit.

The ecu is pretty smart about covering up drop outs and maintaining the master clock 90 degree increments.

[goody90q45]

........I got a CAS code when I unplugged the MAF sensor to see if it would still run. Because before when the car idled worse than it does now it would cease to run when the MAF was unplugged.......

With the MAF plugged in and the ECU codes cleared, what code(s) came back? Just the MAF code or both MAF and CAS? Have both of those connectors been cleaned of corrosion and the connector pins tightened and lubed?

Are all the large (3/4") Exhaust Gas Recirculation hoses intact? Check each hose starting at the air tube connection and work your way back to the valve covers looking for leaks. The connection at each valve cover is very hot and hoses tend to split. I left the bottom hose on the air tube disconnected (by mistake) once and it threw the same code and the engine ran horribly.

[Infinitiguy19]

Well the miss at idle is very small (Barely noticeable to some) but if I put my hand on the plenum (Q45techs way) I can tell there is a miss.

I checked for an intake leak by pinching the hose on the plenum and the idle actually dropped and I could hear the injectors almost close down.

I did not clean the CAS connectors, there so hard to get to but I will try if you think it will make a difference.

I just went out at 10:46 PM with a flash light to look at the hoses and there all fairly soft. And they have been replaced in 2005 so there fairly new with no cracks.

But I will say this: the idle does change from 625 to 750 at the most sometimes, Usually its between 625 and 700.

But the CAS code came AFTER I unplugged the MAF sensor while the car was running. I reset the codes and never cam back after a couple days. I put back the OEM ECU so no Laptop Consult till I put back the 94 Cali ECU.

I will see if there is any change with ECU's (Doubt it).

I also cleaned the ECU connector and checked the harness and it all looked good.

Hey mike when you say "lube" What should I use?

I used die-electric grease and it didn't work out so well, all my connections had a white powder or turned greenish. So i am NOT using that again, Plus Jimmyjimb says its more of a resistor than a conductive.

[goody90q45]

I use dielectric grease but I don't have the weather and moisture issues that you have.

The two sub-CAS connectors need to be cleaned eventually but I was asking about the CAS (distributor) connector that you've already unplugged.

It sounds like a MAF issue (or connector/wiring) more than a CAS problem. You need to meet up with another member and swap MAFs for a short drive.

[Infinitiguy19]

I never removed the CAS connector just wiggled it.

But I have 3 MAF's (2 were re soldered, all 3 were cleaned) I also cleaned and tightened the connections and performed the wiggle test and the MAF was fine.

The closest NICO member with a 1990-1994 Q45 is 70 miles away as far as I know.

[goody90q45]

Clean the CAS connector. It's the same connector design as the MAF. If the MAF connector had green corrosion you can bet the CAS connector does also.

[Infinitiguy19]

I can see one of the connectors (The one with a harness), I can't find the other one thats attached to the CAS with out a external harness.

[xKnownShadowX]

Hi Paul, I see you still have the Q.Well done.Shhhhh........

[qsiguy]

You won't hit redline unless you use the gated shifter and leave it in low gear. In auto it will always shift where it's programmed to. We can set it to 7400 rev limit and it will still shift at the same point unless you force it with the gated shifter.

[Q45tech]

Don't confuse the exact speed when the TCU commands a solenoid to energize and the exact speed when the valve body and system actual completes the movement of gears.

Experience has shown us that this can be 1 second or more delayed.

In first gear near redline SPEED acceleration is ~~~~ 1 mph per 0.1 seconds or less.

[Infinitiguy19]

Hi Paul, I see you still have the Q.Well done.Shhhhh........

Nice signature, Do you have more pictures of the car.

You won't hit redline unless you use the gated shifter and leave it in low gear. In auto it will always shift where it's programmed to. We can set it to 7400 rev limit and it will still shift at the same point unless you force it with the gated shifter.

Right unless according to Wes I install a 1994 Q45 TCU, then it will shift later with that TCU.

But I was talking about reving the car in Neutral when the car is rolling. I will try it in Park at a unpopulated space because my neighbors want my head already LOL.

I also cleaned the CAS as best I could, its fairly easy to do with a metal pick. But I got most of what little green reside there was on the CAS. I did not notice any change sadly. There was not much green stuff on the CAS either, just a little on the base of the male connectors and none on the tips.

Hopefully if the car sits overnight that will change. One thing that will NEVER are my standards on how a Q is supposed to idle and run. Like a good friend of mine always says "Fix the engine first then move on to making the car better".

I also have a ton of ECU logs that I can share if any of you think that would help.
Modified by Paul Wall at 9:15 PM 9/10/2009