Power, accelleration, and knock issues

[mattd1979]

I have a 1990 Q45 (plain Jain) with 162,000 miles and on it's second transmission with 90,000 miles. My problem is that it seems my car just doesn't have the power that it should. My mom has a 91' Q45 with TCS and 203,000 miles with more balls and on it's second transmission with over 100,000 miles. I can't seem to figure out what the problem is. Here is what I have done so far. I have replaced the knock sensors and knock sensor harness, replaced all hoses under plenum, replaced fuel injector spider harness, installed the B&M transmission cooler between condenser and radiator, ran two cans of BG 44k fuel treatment thru the tank within 4 weeks, ran BG fuel injection system cleaner thru the vacuum port that attaches to the brake booster( Per directions from parts man at local INFINITI and will be running another can thru the fuel rails to flush the injectors with the fuel rail flush system), ohmed all fuel injectors which all but one were at 12.5 ohms. The one injector was at 19.9 so I replaced it with one that I bought from PopPop that had been tested and cleaned by a well known company that I can't think of right now. The timing chain guides had been replaced at 120,000 miles according to the receipts that came with the car. Now to give you a taste as to one of the problems I am trying to workout, I was going to lunch at work and I was going to cross the street. The car was in first gear but when I gave it gas, it started bogging for about 5 seconds and then it finally got off its butt and went. This can be a problem when I want to get on the expressway although it only seems to do it every other time. It also seems to lack in power until it gets past 3,000 rpm when it starts to set you back in the seat. My mom's car on the other hand will have the torque and power throughout the power band. My car also has a problem with knock. If I am getting up on the expressway for instance and I put the peddle down half way, it will start knocking and pinging at around 4,000 rpm like it has bad gas. Now I run nothing but Amoco white 93 ultimate and it will still do this with BG 44K in the tank. I almost wonder if maybe the timing had been tampered with and maybe they advanced it. Please, if somebody here has experienced this same problem and was able to fix it, please let me know what you did so I can try to get mine running like it should. Thanks again for all the help you all have given me on this and my mom's Q.Thanks,

Matt Jacksonville, FL
Modified by mattd1979 at 8:24 PM 3/15/2006

[mattd1979]

Bump

[squeefoo]

Have you cleaned your EGR or your throttle body? ...timing checked?

[elwesso]

Things to check and report back:

1. Base timing as read by timing light2. Base timing as read by consult3. not doubting you, but are you sure that the pinging is in the engine? Could it be something else rattling around?4. FSM procedure on Knocking... Main thing to check on this is your EGR.. I assume the car idles smooth... when the car is sitting at idle, lift up on the valve in the EGR valve and see if the engine stumbles or dies. The other thing it has you checking for is an air leak.....

So other than what you've told me, it seems like the problem is intermittant, IE sometimes it will run great (like your mothers car) and other times it will run like crap.....

Hows your fuel pump/fuel pressure.

[mattd1979]

Yes, when I had the upper and lower intake off, I cleaned every little thing that I could get ahold of. Actually when I had the EGR valve loose from the intake I took a flashlight and looked down in it and didn't find any build up. I went ahead and sprayed brake cleaner down in the egr port on the intake. I also cleaned the throttlebody.

[mattd1979]

Hey Wes, I did check the base timing like you said back a couple of months ago when you and I talked and you explained how to hook up the timing light. The base timing was at the stock setting ( I think it is 15 degrees BTC) but I don't know how to check it with the consult. I know that when the consult was connected, it said that the base timing was at 15 degrees but it wouldn't change when I would increase the rpms. When you were explaining to me how to connect the timing light to the engine I first thought that it was my mom's car but later remembered that it was my car. As far as power goes, my car doesn't even have the same amount of back in your seat power as my mom's car even when it doesn't knock.

I am positive that it is detonation knock because of the way it sounds which is exactly how my truck sounds when it starts to knock when I am going up a tall bridge or trying to pass somebody. It has it's own unique sound. It is kinda hard to explain or compare to anything else.

I still have to check my fuel pressure. Not sure exactly how to go about doing that. I don't know if I am supposed to take a fuel pressure gauage and hook directly to the output side of the fuel line going to the fuel rail or have it inline so that I can see what the pressure is as the engine is running.

[elwesso]

I still have to check my fuel pressure. Not sure exactly how to go about doing that. I don't know if I am supposed to take a fuel pressure gauage and hook directly to the output side of the fuel line going to the fuel rail or have it inline so that I can see what the pressure is as the engine is running.

install a T hose into the input (right past the fuel filter) lineand then run the car..

I dont know if its related to your knock..

You already checked timing with a consult, so your golden there..

Only other thing i can see checking is check compression numbers and make sure the plugs arent fouled...

[mattd1979]

I went ahead and jumped off the white wire on the fuel pump to ground and test drove the car. There was no difference in power. I ohmed the fuel pump at .7 ohms. The Fuel pump had been replaced about 60,000 miles ago. I also decided to swap the MAF on from my mom's car to it and there still was no change. The car wants to bog down when you floor it from a stop almost as if you are holding the brakes at the same time. The transmission will also shift normally as it would if you were just easing on the throttle and leaving a light. I also noticed that if I am going about 30mph and then floor it, it will bog and the transmission will hesitate for about 5 seconds and then it will finally drop down into passing gear. But only drop down into second if it is in 3rd. Now in my mom's car, if you are going 30 mph and it is in 3rd gear and floor it, it will instantly drop into passing gear and go and drop down into 1st and then up into 2nd unlike mine. The power between my mom's car and mine are almost night and day. I have run out of things to check other then the plugs. If you read my previous posts in the past you will see that I have pretty much replaced everything that has had to be replaced. Keep in mind that some are of my mom's Q which is a 1991. Mine is a 1990 plain jain. Unfortunately if you were to search for all of my posts, It won't show you all of them for some reason.