Random Multiple Cylinder Misfire

gmcnaples · #1 (**permalink**) 02-03-04, 11:30 AM

I have just spent 500.00 on my '97 ETC with 55,000 miles for a supposed tuneup that included new wiring, plugs, fuel filter, etc., and ultimately a new aftermarket catalytic converter. This was not done by a dealer, but a local shop that supposedly had a good Cadillac technician! The problem is that it is doing the same thing that I took it in for, i.e., really hard starting that grinds and grinds and then finally starts and in traffic a slight lag on acceleration. On the highway, it is fine and very responsive. I took it back, they spent all day on it and read all the codes, and concluded it is the "Ignition Control Module." Their cost for it was 513.00 with tax and one hour to install. I balked at the price, asking how they knew that was the real problem, and they guaranteed that if it wasn't they would then continue to search for the problem at no cost to me (ha). So I then went to gmpartsdirect.com, found the part by the part number they gave me, and including shipping it is $215.00 less, but it is called "Chassis wiring and computer controls." Of course the dilemna now is, they won't order the part from gmpartsdirect.com, and say that if I do, they will install it for one hours labor, but of course, they can't guarantee it....which I understand, but, they said they were 100% positive now (yeah...500.00 later) that would correct the problem LOL)! Can you help?

Here are today's codes

P0101 H, MAF Sensor
P0174 H, Fuel Trim System Lean Bank 2
P0300 H, Random Multiple System Misfire Detected (this is the one they say that tells all and that indicates the above described part is required)
P1599 H Engine stall detected

They say that they checked the fuel system regulator and that it was not leaking.

Any help is appreciated....I am tired of spending money on this car!

BeelzeBob · #2 (**permalink**) 02-03-04, 01:55 PM

How did they check the fuel pressure regulator .....????.... it certainly sounds like that could be the problem....

Those guys are obviously shot gunning this thing to death. Since they didn't fix the problem get your money back for the "tuneup" and all the other unnecessary work they did...LOL

Hope they put the dual platinum OEM spark plugs in as they provide the best performance and longest life. The plugs in that engine should be good for 100K minimum.

You can check the fuel pressure regulator yourself very easily. Just pull the vacuum line off the FPR while the engine is idling and check the vacuum nipple for fuel leaking out of the nipple. Let it idle for several minutes with the vac hose off and check the nipple for the presence of fuel...there should be none. The FPR is the single greatest reason for hard starting like you describe so I would be surprised if that were not the problem.

gmcnaples · #3 (**permalink**) 02-04-04, 08:09 AM

Well, I am a basic mechanic having rebuilt my son's Camaro A/T 350 cube 25 years ago, but I know nothing about the new generation of engines....where will I find the FPR, do I have to remove any cover or cowling....should I have a replacement gasket on hand?

Quote:

Originally Posted by bbob

How did they check the fuel pressure regulator .....????.... it certainly sounds like that could be the problem....

Those guys are obviously shot gunning this thing to death. Since they didn't fix the problem get your money back for the "tuneup" and all the other unnecessary work they did...LOL

Hope they put the dual platinum OEM spark plugs in as they provide the best performance and longest life. The plugs in that engine should be good for 100K minimum.

You can check the fuel pressure regulator yourself very easily. Just pull the vacuum line off the FPR while the engine is idling and check the vacuum nipple for fuel leaking out of the nipple. Let it idle for several minutes with the vac hose off and check the nipple for the presence of fuel...there should be none. The FPR is the single greatest reason for hard starting like you describe so I would be surprised if that were not the problem.

BeelzeBob · #4 (**permalink**) 02-04-04, 12:20 PM

Just remove the silver top cover off the engine by removing the four plastic acorn nuts. Look at the fuel rail that feeds the injectors. At the end of the rail by the throttle body there is a small canister shaped device with a vacuum hose going to it and the fuel return line leaving it. With the engine idling, pull the vacuum line off the FPR and watch the vacuum nipple on the FPR for several minutes for for any sign of fuel leakage. There should be none. Easy and quick check with no gaskets or any special tools required.

Engines are still engines.... Way to much is "blamed" on the new systems and such. Engines still need fuel, spark and air to run.... Getting back to the basics usually allows the root cause to be isolated early in the game.

If you are familiar with engines, then a few minutes with the factory service manual would familiarize you with the Northstar. I would heartily recommend a factory (Helms) service manual if you do not have one already. They are the cheapest thing that you can accessorize your car with to improve it immensely.

Big D · #5 (**permalink**) 02-04-04, 08:41 PM

Quote:

Originally Posted by bbob

Just remove the silver top cover off the engine by removing the four plastic acorn nuts. Look at the fuel rail that feeds the injectors. At the end of the rail by the throttle body there is a small canister shaped device with a vacuum hose going to it and the fuel return line leaving it. With the engine idling, pull the vacuum line off the FPR and watch the vacuum nipple on the FPR for several minutes for for any sign of fuel leakage. There should be none. Easy and quick check with no gaskets or any special tools required.

Engines are still engines.... Way to much is "blamed" on the new systems and such. Engines still need fuel, spark and air to run.... Getting back to the basics usually allows the root cause to be isolated early in the game.

If you are familiar with engines, then a few minutes with the factory service manual would familiarize you with the Northstar. I would heartily recommend a factory (Helms) service manual if you do not have one already. They are the cheapest thing that you can accessorize your car with to improve it immensely.

I just replaced the FPR on my 98 Nortstar. Made all the difference in the world on hard start! Simple fix and fairly inexpensive. The problem I ahve now is that the car has an irregular miss. 98K miles. New plugs and wires at 97K. Miss is around 1900 RPM when I try to accelerate. Slight backfire thru front of engine (pop)! Got any idea for me?

gmcnaples · #6 (**permalink**) 02-05-04, 12:14 PM

Thanks to all for the prompt and courteous replies about this Random Misfire and hard starting. After all this input, I also am inclined to believe that the problem is in the FPR, and I will be checking it this weekend. Obviously, it could cause hard starting, but can it also be responsible for the Random Misfire? If I should try to replace it myself, are there any calibrations required, or is it pre-calibrated?

BeelzeBob · #7 (**permalink**) 02-05-04, 04:55 PM

Quote:

Originally Posted by gmcnaples

Thanks to all for the prompt and courteous replies about this Random Misfire and hard starting. After all this input, I also am inclined to believe that the problem is in the FPR, and I will be checking it this weekend. Obviously, it could cause hard starting, but can it also be responsible for the Random Misfire? If I should try to replace it myself, are there any calibrations required, or is it pre-calibrated?

could cause both....easy to replace....no adjustements or cal required. Just R&R the FPR. Use a new GM part recommended. Comes in a "kit" with the seal and o-ring.