How to Check Timing on 1990 Q45

[slshearer]

I ordered a new Cam Position Sensor and plan to change out the old one, I would like to check / set the timing after the swap, does anyone know what the spec. is and how to check / adjust the timing.

Thanks!Stewart

[Q45tech]

Carefully and slowly because the slot can be set from minus 40 to plus 20 degrees top dead center. Tiny positional errors can be big numerical errors.

I use an adjustable timing light set to minus 15, coupled with the special adapter shown in FSM Proceedure.

[elwesso]

http://www.q45.org

[slshearer]

Thanks for the info, I will let you know how it goes, hope to tame my bronking bull tonight!

Stewart

[slshearer]

Well I changed the Cam Position Sensor & installed a brand new one, but have the same problem, motor shakes at low rpm's. The engine will rev up if I want but you can feel it is not running smooth at higher rpms.

I have always had a wierd problem for years where I would start it up from cold or hot the engine would shake, it was like a plug was bad the motor would shake the car and run rough, after a minute or so it would smooth out and run like new, this might happen once every couple of months or more.

A few weeks ago I pulled off the interstate and stopped to grab a sandwich at MDees, came out tried to start the car and it would not fire up, after 3 try's it started acted like it was flooded, engine was shaking as previously described. Anyway went down the interstate and the car was running awful, hestiating and surgiing (the check engine light came on) first time I ever saw that light since I got the car in 1992,so I pulled off and opened the hood, I could see the engine shaking and heard a clicking ? ticking sound, sounded like a bad pushrod or lifter so I drive slowly to my destination at a slow speed and parked the car.

After a couple of hours I got back in, hit the key and it ran perfect! No rough idle, no check engine light so I drove home about 30 miles ran great. I decided to take it to Gwinnett Infiniti and have them do an inspection and pull the error code, the only code was one for the Cam Postion Sensor they also adjusted my timing at the same time.

about 3 days ago it started running rough again when started only it has been running this way since then, today I replaced the Cam Position Sensor, I approximated the same position as the old one and it started right up but the rough idle is still there, The check engine light is off and I am stumped, I did a complete service at 180K, all parts were Infiniti, new belts, Infiniti air, gas filters, B44K in the tank, rail flush, water pump, alternator, all new hoses under the plennum etc.. etc..

I called 3T auto in Roswell today and spoke with someone there and they said I needed all new injectors and it was because of the reformulated gas had damaged my injectors and would cost $2200 to have the service done, I was surprised he could diagnose my problem over the phone and well.... I wasn't impressed with his explanation since he had not seen the car!

Any ideas?

Thanks!Stewart
Modified by slshearer at 9:37 PM 7/23/2008

[goody90q45]

Ohm your injectors yourself and make your own diagnosis. No tools required other than a voltmeter and it won't take 5 minutes. It sounds like dead and dying injectors to me too but probably not all 8 of them.