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gsanche7
04-04-2012, 12:08 AM
i have a 2001 grand am and i need Help or some type of guidence to finding the problem i have. .... so heres the rundown i swap a 3.5 Lx9 engine into my grand am i got the car to turn on it idles rough and when i drive it it feels like it has no power in between the rpm ranges of 3000 and above the car starts backfiring. PLZ!!!! SOMEONE HELP !!

chris_gt_74
04-04-2012, 12:14 AM
i have a 2001 grand am and i need Help or some type of guidence to finding the problem i have. .... so heres the rundown i swap a 3.5 Lx9 engine into my grand am i got the car to turn on it idles rough and when i drive it it feels like it has no power in between the rpm ranges of 3000 and above the car starts backfiring. PLZ!!!! SOMEONE HELP !!

Did you install the external crank sensor required for the swap? Your timing sounds screwed up.

gsanche7
04-04-2012, 12:23 AM
yes i did install the external crank sensor , do u think there might be something wrong with either the 7x or the 24x sensors?

chris_gt_74
04-04-2012, 12:54 AM
I don't know much about a 3500 swap but I wouldn't rule out. Is this a recent swap or was it running fine prior to now? I'd check all sensor connections and double check you firing order is correct. Outside of that a 3500 swap experienced person should step in and advise you if they can.

2kSCT
04-04-2012, 01:13 AM
Hey, I'm having basically the same problem here after my 3500 swap. Is yours more like a misfire that only happens when your car downshifts for passing or trying to go faster? Did you do any modifications to the exhaust by any chance? When I did my swap, I also got Milzy's headers and high flow cat along with my Borla catback so one idea being thrown around is insufficient back pressure. Mike at Milzy suggested the ICM could be bad and everyone else is basically saying check over everything and make sure it was done right.

gsanche7
04-04-2012, 01:15 AM
it is a recent swap ill go thru all my coneections tomarrow .and am hope ing someone esle could further help me but thank you for your help .

gsanche7
04-04-2012, 01:23 AM
well i do have exhaust mods to my car i have pace headers and a magnaflow cat back and no cat but my car doesnt misfire its just more backfiring and no power in between the 3000 rpm and above and i am thinking its more about timing on my car. on your car you should check and run it with a obd2 scanner that can read misfires so you could locate the misfiring cylinder and go from there.

2kSCT
04-04-2012, 01:25 AM
Well your problem is almost identical to mine so once you figure it out, let me know haha. It's probably something easy like a sensor or something but eh... Good luck and keep us posted!

2kSCT
04-04-2012, 01:33 AM
I'm not so sure it's a misfire. Backfire seems more appropriate I guess. I try to accelerate and the car says no way in the form of a very aggressive loss of power and "blap blap blap!!" of the engine. I cannot push past the backfire and holding the throttle doesn't make it better or worse, just constant. Obd2 and tech2 both showed no signs of a missfire code so my diagnosis of a missfire must be wrong and it is indeed a backfire. Day to to driving is fine except for the random stalling at red lights but I'm starting to think that could also be somehow related. A crank sensor could very well be our problem. How much of a gap do you have between the trigger and crank pulley?

gsanche7
04-04-2012, 01:53 AM
okay now that sounds more like my problem LOL that blap blap blap sounds like mine and on the random stalling mine does it to. the gap that i have i dont now now but my trigger is not adjustible. so i would need to check with a caliper. but i did see in another post that the 7x sensor (the trigger one) along with the pcm controls timing above 3000 rpm.

gsanche7
04-04-2012, 01:54 AM
so am thinking the 7x sensor might be the problem

2kSCT
04-04-2012, 01:55 AM
Is that the one on the trigger?

gsanche7
04-04-2012, 01:57 AM
yeah it is

2kSCT
04-04-2012, 07:48 AM
I put it on right but there's not exactly a way to adjust it so where does that leave us? New sensor? People have said to make sure it's mounted properly but there isn't a way to mess it up so that's just more of an insult than a piece of advice.

chris_gt_74
04-04-2012, 08:46 AM
I put it on right but there's not exactly a way to adjust it so where does that leave us? New sensor? People have said to make sure it's mounted properly but there isn't a way to mess it up so that's just more of an insult than a piece of advice.

Not necessarily lol. I swore once that I installed my clutch on an old truck correctly and it had to be something else but when I pulled it as my last resort to check it was in backwards after all. Double checking things should be a standard practice IMO cause you never know. Judging from the part list for Milzy's swap kit the crank sensor, camshaft sensor and map sensor pigtail is where I would start. All 3 can cause the car to drive badly. Then again it may be completely unrelated. I'm just trying to help out.

gsanche7
04-04-2012, 09:37 AM
Amma try swapping the 7x sensor today to see if thats the problem

2kSCT
04-04-2012, 12:01 PM
How big is your gap between the pulley and sensor?

Starglow
04-04-2012, 12:32 PM
I put it on right but there's not exactly a way to adjust it so where does that leave us? New sensor? People have said to make sure it's mounted properly but there isn't a way to mess it up so that's just more of an insult than a piece of advice.

Yes it IS adjustable, but it's not obvious that it is....LOL! 8-)

Loosen the crank sensor bracket mounting bolts which should allow some play for adjustment. The gap between the sensor & trigger wheel should be no more than .040 based on everything I've read on the subject.

Just curious as to what fuel injectors you guys are running and if you had a PCM tune done? I'm thinking either the injectors are maxing out at higher RPM's or the PCM is making improper adjustments based on the old 3400 engine specs which might also explain the stalling problem.

gsanche7
04-04-2012, 03:11 PM
I am running a stock 3.4 fuel rails and pcm but am currently working on the tune wit my hp tuner programmer

HOYS
04-04-2012, 03:35 PM
How big is the gap between the sensor and the trigger wheel?

gsanche7
04-04-2012, 04:21 PM
about .35

mfuller
04-04-2012, 04:35 PM
Are you sure you didn't mess up the order of the spark plug wires?
That could cause a nasty backfiring.

2kSCT
04-04-2012, 06:20 PM
Mixed up wires would cause a very rough idle, one that would be noticeable before backfiring at 4k rpm. So I'm guessing the closer the better is the case when it comes to the trigger kit? Mine seems far away but voltage readings done at school today showed about .5v from the sensor while cranking.

AaronGTR
04-04-2012, 06:22 PM
It definitely sounds like a crank sensor to me... for both you guys. You don't want back pressure in the exhaust (back pressure is the enemy) and neither one of you have large enough exhaust tubing with those mods that it would cause a really significant loss of low end torque. It also wouldn't account for loss of power or any backfiring/misfiring above 3000 rpm.

The 24x crank sensor actually only controls timing up to 1600 rpm. At 1650 and above the ignition control module converts the 7x crank signal to a 3x reference signal for the PCM for timing control. According to my manual though, the 7x sensor is the most critical. If that is not present, the engine won't run. If it is present, but it's not sync'd up with the cam sensor signal, then it will run at a default low timing that is built into the ICM. If that's the case though you should get a DTC code P1351.

I would say the problem is probably either with the coils, the ICM itself, or the 7x sensor. You might need to check and adjust the trigger wheel and/or the sensor mounting, or even replace the sensor. If you have a scanner/tuner you should be able to see any codes present and see if the timing is bouncing around like normal above 1600rpm or if it's running at default.

2kSCT
04-04-2012, 07:17 PM
Well the coils I have are the msd ones and I also have the 8.5mm wires. I started testing resistance in the coils at school today and found that one of the posts on the far right tower was more brown than all the other coils' posts. Probably unrelated... Ethos scanner and tech 2 both show no new codes and not even a misfire code.

AaronGTR
04-04-2012, 09:13 PM
Try swapping your stock coils back in if you still have them and see what that does. I had two MSD coils go bad on me. It may have been a problem related to the coil pack adapters for the DIS-4 ignition box I was using at the time, but it also may have just been bad coils. Anyway it's worth a try and eliminates one more possibility if that doesn't fix the problem.

HOYS
04-04-2012, 09:52 PM
Check spark on each cylinder and make sure your wires are on the proper cylinder.

Also, I might be in Riverside within a few months if your still having problems, Moreno Valley to be specific...

gsanche7
04-04-2012, 10:02 PM
If the cables were messed up i would defintetly get a misfire code but i dont get on on any scanner.

gsanche7
04-04-2012, 10:06 PM
Try swapping your stock coils back in if you still have them and see what that does. I had two MSD coils go bad on me. It may have been a problem related to the coil pack adapters for the DIS-4 ignition box I was using at the time, but it also may have just been bad coils. Anyway it's worth a try and eliminates one more possibility if that doesn't fix the problem.

And i am using the stock coils but still having the same problem . i am curious if this code has anything to do with the backfiring problem (P0620) it comes up because of my bad alternator

locoman99
04-04-2012, 10:15 PM
And i am using the stock coils but still having the same problem . i am curious if this code has anything to do with the backfiring problem (P0620) it comes up because of my bad alternator

Wait a second...u know u have a bad alt? Change it. A failing alt can make your ignition do crazy things

gsanche7
04-04-2012, 10:18 PM
yeah i went to go get one today and amma change it tomarrow.

2kSCT
04-04-2012, 10:27 PM
I don't have the stockers any more.there's a 01 gt at the j/y that has some on it, chances are they're still good lol. Where is the ICM exactly?

chris_gt_74
04-04-2012, 10:30 PM
I don't have the stockers any more.there's a 01 gt at the j/y that has some on it, chances are they're still good lol. Where is the ICM exactly?

I always thought it was the plate the coil packs plug into.

2kSCT
04-04-2012, 10:34 PM
That would make since... But it's just a plate and there's not really anything "module" about it haha. Well, when I was checking the coils, I noticed one prong was kinda angled to the left, outward if you will. This is interesting because that also happens to be the same coil that has the darkened brass post. Could the angles prong be causing a bad connection making the current arch which browned the post and possibly damaged the plug wire?

gsanche7
04-04-2012, 10:34 PM
to see the icm remove the ignition coils and the icm is the one that ur coils are plugged into.

gsanche7
04-04-2012, 10:45 PM
which junk yard ? u saw the icm and coils at i call dibs :D jk

2kSCT
04-04-2012, 11:35 PM
The off milliken in Ontario. It's like 4 blocks from my school so it's not hard to stop by there on the way home. Is an alero ICM and coil pack the same as ours?

gsanche7
04-04-2012, 11:52 PM
i have been to that one and as long as it is a 3100 or 3400 it should be the same

2kSCT
04-05-2012, 01:03 AM
I thought so. Today I was there and got a front right quarter panel for $50. Scooooore haha

AaronGTR
04-05-2012, 04:24 PM
That would make since... But it's just a plate and there's not really anything "module" about it haha. Well, when I was checking the coils, I noticed one prong was kinda angled to the left, outward if you will. This is interesting because that also happens to be the same coil that has the darkened brass post. Could the angles prong be causing a bad connection making the current arch which browned the post and possibly damaged the plug wire?


It might not look like it, but it is in fact a module. It has three harness plugs on it, and connectors for the three coils. The circuitry is hidden inside. And yes, any problem or anything out of the ordinary with the ICM could be causing your problem.

2kSCT
04-05-2012, 04:34 PM
Well I just got back from the j/y with 3 new coils and an ICM and I guess we're gonna see how that works.

2kSCT
04-05-2012, 07:50 PM
Well swapped in the J/Y ICM, test drove it, still did it. Swapped in the J/Y coils, test drove it, still did it. So I guess from here it's either the exhaust back pressure or crank sensor. I had a feeling that wasn't gonna help because my MSD coils are... Well MSD and the ICM worked fine before the swap. Ugh I don't know what to do...

gsanche7
04-05-2012, 08:52 PM
U still havent found a solution ? Damm .....u should have got some crank sensors .

locoman99
04-05-2012, 09:07 PM
Well swapped in the J/Y ICM, test drove it, still did it. Swapped in the J/Y coils, test drove it, still did it. So I guess from here it's either the exhaust back pressure or crank sensor. I had a feeling that wasn't gonna help because my MSD coils are... Well MSD and the ICM worked fine before the swap. Ugh I don't know what to do...

No such thing as "too little backpressure"

2kSCT
04-05-2012, 10:11 PM
Where did I say "too little back pressure"?

2kSCT
04-05-2012, 10:24 PM
So I went outside to mess with the kit a little bit. I think I'm going to assume that the problem is that the sensor is too far from the pulley. I don't have a feeler gauge to measure the gap but I think I could probably fit a nickel in between there if not something thicker. Also the mount feels a tad bit loose. If I had to guess I would say it moves about .005" haha. I can't see it wiggle but I can feel it. So now I gotta go get some 1/2" allan wrenches because simple hex bolts would have been too easy for Milzy to use... Haha. So ideas on maybe getting the sensor closer? A hammer? Haha

locoman99
04-05-2012, 10:25 PM
Hey, I'm having basically the same problem here after my 3500 swap. Is yours more like a misfire that only happens when your car downshifts for passing or trying to go faster? Did you do any modifications to the exhaust by any chance? When I did my swap, I also got Milzy's headers and high flow cat along with my Borla catback so one idea being thrown around is insufficient back pressure. Mike at Milzy suggested the ICM could be bad and everyone else is basically saying check over everything and make sure it was done right.

Here.

HOYS
04-05-2012, 10:57 PM
You can blame Marc from TCE for the allen head bolts. :p They might be metric...but I'm pretty sure Marc uses standard for most fasteners.

gsanche7
04-05-2012, 11:21 PM
I think we should try the 7x crank sensor ... question 2ksct does your car throw a battery code like on the intrument cluster?

2kSCT
04-06-2012, 12:40 AM
Yeah it does every now and then. Sorry about the size but I uploaded I from my busted iPhone so I don't know how to change it :D

http://i1092.photobucket.com/albums/i411/sn0tr0cket1989/62ab1d55.jpg

Starglow
04-06-2012, 06:41 AM
That gap is too wide. Think in terms of .040 spark plug gap to get an idea of the correct spacing. You should invest in a feeler gauge set...they aren't very expensive.

If the sensor feels loose, then it's going to vibrate while the engine is running which may contribute to the problems you're having. Did you apply any locktite to the bracket bolts when you installed them? If the bracket feels loose, then those bolts are going to start backing out over time.

2kSCT
04-06-2012, 07:31 AM
Well that won't move it closer. If anything tightening the bracket more will probably more it further. Is there a way to bend it just a tad bit?

gsanche7
04-06-2012, 04:21 PM
i moved it as close as possible mine had alot more space to give and that was the problem i suggest u drill out your bottom hole bigger so it can get closer mine runs like a champ now!!!! :):)

AaronGTR
04-06-2012, 06:10 PM
^I'm thinking this may be the solution. And I also agree with starglow... get a feeler gauge set. They are cheap and you can use them for other things like checking spark plugs gaps too. Try and get the sensor as close as possible and see what the gap is. If it's more than the maximum gap they recommend, try drilling out the bottom hole on the bracket over size slightly to give you more adjustability. And I would definitely use some locktite on the bolts. The bracket shouldn't have any movement in it. You don't want that sensor moving around while the engine is running.

2kSCT
04-06-2012, 10:01 PM
Problem solved. Let this thread die the most painful death a thread has ever died.

Woooooohoooooo!