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GA SE/T
09-02-2006, 10:24 PM
Kinda long, so for those who are too lazy to read it all:

Short.....
Old LD9 died, replaced w/ rebuilt LD9. New motor has random misfire, car was diagnosed. DTC: P0300 found. Replaced spark boots/plugs, coils, & coil housing. Still having issues. Need suggestions/help. Owner is ready to shoot someone.

Long....
So, literally Iíve been pulling my hair out trying to diagnose and cure this problem. I recently replaced the original LD9 from my car as I spun bearing #1. Now I have a new/rebuilt LD9 which was installed with no major issue(s). So after driving around for a couple of days, I noticed this ďrockingĒ movement that the motor makes while at idle; say at a stop light for example, feels like a very rough idle. So Iím :nervous: . With no CEL/SES light, I take the car in for diagnostics. Found stored code: P0300(multiple/random misfires). So Iím :bleep: . The tech found evidence of spark leak from cylinders 1 & 4. The tech recommended I replace the top coil housing and spark boots. I replaced what was suggested and I also went further and replaced the coil packs and spark plugs. The plugs were torqued to 13-ft lbs and gapped to 0.050inch (GM spec). Mind you, everything was replaced with all the overpriced GM OEM AC Delcro crap and the ****ing car does the same crap!!!
Someone suggested that I do a crankshaft relearn procedure as a new motor was installed and the ECM is calibrated for the old motor. Could this be a factor? According to my Haynes manual, it does say that if the crank position sensor is ďrepositionedĒ/moved, it could cause a random misfire DTC and should get this procedure done. Well, the sensor wasnít necessarily ďrepositionedĒ but it was transferred from one motor to another. I think itís a good idea since Iíve done just about everything else, and it will cost ~$90.00.
Anyone have any suggestions on where to go? I have a new motor in the car and I canít stand the fact that itís running like a POS. Another part that was suggested to change was the FPR, but I don't know. Please help!

Other stuff performed:
Changed upstream O2 sensor
Fuel injector system clean/flush
Replaced fuel filter

Car info:
2000 Grand Am
2.4/auto

lone_wolf025
09-03-2006, 09:40 AM
I got nothing new for ya, but I'd say definately get a case learn done. Concept is that the comp looks at the crank sensor for precise timing and if it wasn't exactly where it last left off it could cause issues. So get the relearn and go from there.

Sprucegagt
09-04-2006, 12:12 AM
I would do a compression check before anything else. Even new/rebuilt engines can be down on compression.

GA SE/T
09-05-2006, 06:55 PM
I would do a compression check before anything else. Even new/rebuilt engines can be down on compression.

Cool. So I took your advice and the results:

Test 1: C1=> 171 C2=> 175 C3=> 175 C4=> 184 ==> 176.25PSI Avg.

Test 2: C1=> 173 C2=> 176 C3=>176 C4=>186 ==> 177.75PSI Avg.

{2.4LD9 spec: 100PSI(min) w/ maximum variation of 30% between each cylinder.}

Test was done at normal operating temperature. So cylinder 4 is a little higher than the other 3, but <30% variation of the other cylinders. Pressure climb on gauge was consistant for each cylinder {pressure build up was quick and consistant}. So after this test, I'm going to say that the motor is good. :clap:

I got nothing new for ya, but I'd say definately get a case learn done. Concept is that the comp looks at the crank sensor for precise timing and if it wasn't exactly where it last left off it could cause issues. So get the relearn and go from there.

I think this is the next step I'm going to take. It has been in the back of my mind but I have been putting it off. I will be doing this hopefully tomorrow and I will post results wether good or bad.

If anyone else has a clue, chime in please, because I'm going to :cook: with this car!!!

Sprucegagt
09-05-2006, 10:16 PM
Did you use the fuel injectors from the old engine or the new one?

2ciz2nv
09-05-2006, 10:50 PM
It might be your spark plugs, what kind to you have? I used Bosch ones and my ride misfires like crazy. After going to the dealer I was told that Bosch plugs are the worst ones you can use.

GA SE/T
09-19-2006, 02:01 AM
**UPDATE**

Sorry I haven't been updating, I've been very busy in my work/personal life. I replaced my FPR and my drivability was improved instantly. When I drive the car around, it drives smooth. From what I can tell, it's not missing while driving. But now when I come to a stop, the car idles rough and misfire is definately present. At every stop light, I have to put the car in neutral to "calm" the motor. So basically, the car only acts up only at a stop. It still does the exact same stuff as previously noted from my other posts. During warm up, it's ok as far as idle goes, still a little rough, but as the motor temps up and RPM's drop, the problem arises.

So I took my car to my usual dealership to get the crank case re-learn done, but they were too busy at the time and couldn't see my car. Well, I have a life and didn't have the time to wait, so I went to another dealership down the street. I had another GM tech look into this issue. His exact words were that the crankcase relearn would not help in this situation and he thought that it is the motor off timing (exhaust cam tooth) and that's what is causing the misfire. He also said that the case relearn is only for the rev limiter. :erika: So now I'm :confused: . He suggested that they could look into it but they would have to dissassemble the timing chain cover to make sure everything was sound and that takes an average of 6hrs x $90 an hr = $540. HAHA!!!!! No way am I going to pay that money.
I called the company that rebuilt the motor because they have a 3yr, 36,000 mile warranty on the rebuid. I talk to their tech and gave him all the info I have and he is certain its not the timing/rebuild mainly because if the exhaust cam was off, he said the compression would be all over the charts. He suggested that it may be a fuel issue. I'm still confused....
The moral of the story is that I'm tired of investing more and more money trying to figure out this problem. I've been putting off the case relearn, so I'm going to finally give it a shot tomorrow and hope it works. *crosses fingers*

Any help/suggestions would be appreciated.



Did you use the fuel injectors from the old engine or the new one?

Yes, I did use the old injectors from the original motor. Checked them with a noid light, they are working, but in correct timing, I do not know. I will ohm them out to check for impedence and match them to spec.

=ciz2nv] It might be your spark plugs, what kind to you have? I used Bosch ones and my ride misfires like crazy. After going to the dealer I was told that Bosch plugs are the worst ones you can use.

I did start out with Bosch Platnium, but when I replaced the coils and spark boots, I went with AC Delco. Gapped to 0.050 inch and torqued to 13ft-lbs. Still no luck. ;crap

Sprucegagt
09-19-2006, 07:44 AM
Yes, I did use the old injectors from the original motor. Checked them with a noid light, they are working, but in correct timing, I do not know. I will ohm them out to check for impedence and match them to spec.

I would swap the old injectors for the new ones and see what happens. The old injectors could of been dirty and in moving them over, dislodged the dirt inside and partially clogged them. I would not pay for a case relearn yet.

GA SE/T
09-22-2006, 09:41 AM
I would swap the old injectors for the new ones and see what happens. The old injectors could of been dirty and in moving them over, dislodged the dirt inside and partially clogged them. I would not pay for a case relearn yet.

As promised, I ohmed out all 4 injectors and the results:
C1: 24.4ohm
C2: 22.8ohm
C3: 21.3ohm
C4: 20.2ohm

Looking in my Haynes repair manual, for a 2000 w/ out EGR, injector resistance should be 11.4-12.6ohms. Hmmmm.....I think mine are kinda off. ;crap
I guess this will be my next thing I will have to swap. Do you think this could be a major contributor to my issue(s)? I would assume since their resistance is high, they in turn might be "lazy" or not allowing sufficient fuel delivery. This sucks either way.
:hang:

GA SE/T
09-27-2006, 05:52 AM
So does anyone know where to get 4 new fuel injectors at a "reasonable"(<$100 each) price? I need all four and I know it's going to be expensive. :banghead

Sprucegagt
09-27-2006, 07:07 AM
Why can't you use the injectors that came with your rebuilt engine? Did you check them?

GA SE/T
09-27-2006, 03:57 PM
Why can't you use the injectors that came with your rebuilt engine? Did you check them?

The reason is because the new engine did not come with new injectors. I had to reuse my old ones from my old motor. I should've checked them before install, but the funny thing is that I didn't have any problems with them on the old motor......:iconfused

MMGT1
09-27-2006, 05:41 PM
Wreckers bud. Don't buy new. No need. Find a car wrecked with low miles and pull em. The whole set should cost a hundred or so.

Sprucegagt
09-27-2006, 10:44 PM
The reason is because the new engine did not come with new injectors. I had to reuse my old ones from my old motor. I should've checked them before install, but the funny thing is that I didn't have any problems with them on the old motor......:iconfused

My bad, I thought it came with them. Then I would do what MMGT1 suggested if your looking for them cheap.

GA SE/T
10-27-2006, 06:43 AM
Soooooo
Well I got back into town and I replaced all four injectors and guess what?.........:whistle: The car still does the same crap!!!! :rage:

So after spending more money, I'm back to square one. So I've been thinking about the install and the things that could've gone wrong. So now lets say the engine is working properly, I'm now leaning towards the torque converter. Now could a torque converter that wasn't seated properly cause my issues(s)?

Below is a detailed outline of what is happening with the car:
Random Misfire (PO300) code set.
Shudder/misfire when at complete stop (600RPM).
No flashing/solid SES light.
Trac light comes on when engine is idle for long periods of time.
When cold, engine will bog down to the point of almost dieing, but does not, engine continues to run and warm up normally.
Shudder/misfire when driving up hill (very noticeable).
Slight shudder/misfire at 45+mph at 1,500RPM.
Shudder/misfire in all gears. Shudder is reduced when placed in neutral.
Engine does NOT lack power when moving from dead stop.

I'm pulling crap out of my head right now as I'm running out of ideas. I have a shop that can do a complete diagnostics except it will cost me $300.00 and I will have to be with out the car for 3 days min. :( Any other suggestions are welcome guys. I'm about ready to drive this car off a cliff. :crying:

GA SE/T
10-29-2006, 11:53 AM
Anyone???? :attention ;crap :confused: :duh: :nervous: :)

Sprucegagt
10-29-2006, 07:11 PM
Soooooo

Trac light comes on when engine is idle for long periods of time.


Wait a minute. Your traction light comes on at idle? I take it without the car moving? When traction control is engaged you will get a miss. It makes me think your problem is associated with that light. I would be checking out if its your speed sensors, wiring or PCM.