'99 Q45 Acceleration Cutout & Hard Start

[Jim1999Q45]

Hi. I'm newly registered but have gotten good info here over last 3 weeks. Thanks! Cuts out bad when accelerating. I checked timing-- was about 18 degrees BTDC when should be 15 degrees at idle. Rotated Cam Sensor to adjust to 15-- ran worse. Adjusted other way to 25 degrees BTDC. Runs much better, so it's probably not injectors or coils (phew). Know that Knock Sensor (code comes up) retards ignition if senses knocking (& if going bad?). Am I just compensating for a bad Knock Sensor by adjusting the timing? Hard start may not be related. Inf. dealer said auto choke was sticking, but they also said acceleration issue was probably bad coils. After $420 at dealer for fuel pressure regulator, no improvement. Thanks in advance for any response posts!

[Infinitiguy19]

Put it back to 15 degrees, and see if the coil packs are still good. FGY33's are known for bad coil packs.

Welcome to NICO.

[maxnix]

Are you sure your readings are correct?

Precisely describe the method you are using to determine timing.

[Jim1999Q45]

Clipping inductor around the "loop" by the firewall, per service manual instructions for "manually" checking timing (a new one on me). Timing marks noted per manual, since the # of degrees aren't indicated by any of the marks. Adjusted timing by rotating camshaft sensor, per instructions.

Reviewed other helpful posts on this site, and the problem might be the throttle body. Bought the Valvoline throttle body cleaner recommended, and will clean it thoroughly tommorrow and report back. It might fix the hard starting, but I'm not holding my breath on the acceleration problem. May have to replace a knock sensor, after all.

[maxnix]

What are you using for a tachometer?

[Jim1999Q45]

Dashboard Tach. At idle (1k) and 2k RPMs. Should be 15 & 25 degrees BTDC, respectively.

[maxnix]

You need to use a Tach/Dwell meter that is more accurate and has larger gradations.

Can't believe it can run at 25° BTDC.

Are you disabling the IAC valve?

[Jim1999Q45]

Not disabling IAC valve. Unplug connector, first?

[Jim1999Q45]

I read the service manual more closely. After warming up the engine, turn it off. Disconnect Throttle Position Sensor harness. Restart engine. Check timing. (6 marks-- 0-25 degrees, left to right.

Also, I cleaned the throttle body and both problems are much improved. Now I'll check the timing CORRECTLY and report back.

[Infinitiguy19]

What if you clean the whole intake then try to set the timing? Clean the IAC valve, plenum and what ever runners it has as well.

[Jim1999Q45]

Thanks for your thoughts!

I cleaned the IAC valve last week, at least while connected to that unit it's attached to. The "thingie" moved without sticking when I turned the key on.

I'm thinking about getting a gasket and taking the throttle body off to clean it. Is that what you meant by "whole intake"? Cleaning it in-place seemed to really help-- until I started messing with the timing.

Timing: There are two Throttle Sensor harnesses (only one to the Secondary Throttle Sensor). I disconnected the top one, but that didn't change timing readings. Couldn't start the engine when both harnesses were disconnected. So... I timed it "by ear" as it got dark, and will work on it more tomorrow. Might try disconnecting the bottom one, only.

[bullittandy]

Remember Occam's Razor-the simpler solution is the better one.

Coils are notorious on these cars-start there. Knock sensors also fail regularly and cause sluggish performance. Hard start is also endemic to these cars-it may be "normal."

-A

[Jim1999Q45]

KNOCK SENSOR????

Thanks! Two shops told me I was getting a knock sensor code last month, but they didn't seem to think that was main issue-- The MAF sensor was bad this first time. And I thought the Knock Sensor code might just be from a tank of mid-grade when gas prices were at the peak (I won't do that again). I've cleared the MIL twice since then (battery disconnect), but it's back on again. I'm waiting for a friend to lend me his code reader. I know there's one on the inner side of each bank, but until I start taking stuff off, I can't tell a knock sensor from the O2 sensors. I'll use the code to zero in on the bad one (left or right bank). Is replacing a knock sensor a major headache?"

The hard starting is a recent development, and seemed to go hand-in-hand with the other problem.

Jim

[BadQ45t]

My 97' has 90k and stilll okay but lots of knock sensors are bad around 120k for our Y33 2nd gen Q's. If your over 120k replace the knocks sensors just out of routine and see where you end up.