Chevrolet Colorado & GMC Canyon Forum banner

1 - 8 of 8 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter #1
Not sure of time frame.mabe 2 years ago 13,000 miles ago. I blew up the engine on 2008 colorado LT 3.7engine 4wd .Purchased new rebuilt jasper engine long block, no issues on install. heres what is happening from day 1 of motor install.. get in truck could be any time hot or cold out. Start truck. Sometimes it starts right up most of time will not start right away then it lops runs rough sometimes will stall out.Then as soon as its warmed up it runs perfect i have driven it an hour up the free way no problems no misses nothing ..stop shut if off and it will not start turn over 3 or 4 times and same story runs terrible up the road for a few hundred yards then runs great again... This is what i have done checked all plugs there new and clean. new temp sensor in block new mass sensor ..new map sensor... cleaned throttle body... new cam sensor;... new crank sensor..; new fuel pump. purchased fuel pressure tester holds fuel pressure perfect. although my cheap scanner told me I had an evap leak I replaced canister solenoid and purge solenoid valve on engine block and blew out charcoal canister 1 tiny puff of dust come out . two new O2 sensors...new cam actuator solenoid.. So correct me if im wrong im not a professional ..the engine is new don't think its timing because runs great after warm up no misses or back fires ..I took truck to GM dealer and had computer what they called reflash after motor install over $100 same problem in end . Returned truck month later paid over $100 again to have this issue trouble shoot with good equipment. When I picked truck up they could not give me a definitive answer all they said and I don't understand it. He said when i was lookin at the computer sometime it was missing info??? you may have a bad PMC or something he did not sound sure .. that so what should I do get a new PMC $280.00 plus another $100 to set up never had issue before the motor blew up ..Can any of you Good people point me in some kind of direction...thanks .... jim
 

·
Registered
Joined
·
6 Posts
Jim, I had an similar problem like yours in my 07 Coly 3.7 when I replaced my crankshaft and rod bearings. I left the head on and had the engine turned upside down on a makeshift stand. For some reason the #2 fuel injector was sticking after that and not sealing properly causing a long crank and poor running on restart after reinstall. I ran a couple of bottles of Techron Complete fuel injection concentrate and that helped somewhat. I'm going to replace all the injectors at some point but I'm not looking forward to that job right now.
 

·
Registered
Joined
·
1,322 Posts
Good diagnosis. That's the first thing that came to my mind too until you said it held fuel pressure. So, you hooked up the fuel pressure gauge and turned it over until the gauge showed good pressure and then you let it sit for a while and the pressure didn't drop at all? Fuel pressure leak down and flooding one of the cylinders would certainly cause the problems you describe.
If you don't own a fuel pressure tester, in the morning before you get in and turn the key, open the hood and stick something in the schrader valve where you normally hook up the fuel pressure tester and see if you have good pressure. If you have a fuel pressure tester, just keep it connected over night and check in the morning and see if you have good pressure.
Let us know what you find out. You've thrown way too much money at this problem not to have any positive results.
 

·
Registered
Joined
·
5 Posts
Discussion Starter #4
Ok two months later still at a loss Colorado 3.7 runs terrible at cold start up. Then runs absolutely perfect after a few mins, drive anywhere any length of time no miss anything. Shut off and restart runs terrible first minute or so . I looked at secondary air injection tested relay good replaced the connector. Replaced the mass sensor and new air filter, replaced connector harness at map sensor. My $139 scanner says map and mass sensors preform ok cleaned the map sensor with recommended cleaner and also checked cam actuator solenoid was clean but had replaced it last spring. When I had the truck to GM to have this problem scanned so I could fix this they just said I may have a bad PMC so replaced the PMC had crank sensor and key relearn only to have same problem ....So the scan tool keeps throwing a P01174 air fuel mix and more then any other a P0366 cam position sensor code. I have replaced it 3 times. OK the motor is bran new. I think it should not be a timing issue???? because if it was would it run bad all the time? Also i read somewhere continual cranking can throw that p0366 code when I try to start . Ok this is where i'm at 2 months later . I'm not a expert just a back yard mechanic I'm looking at 2 more things No 1 when this new engine arrived complete long block vin e 3.7 the top of block had 2 separate holes for two camshaft solenoids my original motor only had 1 and one connector thinking they sent wrong motor I called them they said it did not matter just use one sensor and plug the other hole. I used a old sensor to plug the other hole. Could this 2nd sensor because it has a magnet in it be causing a problem even though it has no connector??? I know that probably made me sound like a complete idiot but looking at every possibility. No 2.. although I cleaned the throttle body I;m thinking about replacing it if it may help the air fuel mix honestly I don't know what to try next..
 

·
Registered
Joined
·
1,322 Posts
Sounds like you're throwing a ton of money at this problem. 2 things come to mind. A bad fuel injector, or a bad O2 sensor. If an injector isn't closing all the way, it will drain the system of fuel pressure while sitting, then it will take a while to start, because it needs to build fuel pressure, it will then run poorly because you have a flooded cylinder. Do a fuel pressure test before you crank it in the morning. Getting a bad fuel/air mixture can be caused by a faulty O2 sensor.
 

·
Registered
Joined
·
6 Posts
Jim, I would suggest holding the gas pedal to the floor when cranking the engine cold which would put the engine in the "clear flood mode". If the truck starts without extended cranking, the problem is narrowed down to a fuel related problem. I'm still guessing you have an injector issue like I had in my previous post. I'd try Old Guys suggestion first since we both think your problem is more fuel than anything else
 

·
Registered
Joined
·
38 Posts
If you have a leaky injector a quick check is to pull your oil dipstick and give it a sniff and check for the odor of fuel. The fuel that leaks into a cylinder from a stuck injector will seep past the rings and contaminate the oil.
 

·
Registered
Joined
·
5 Posts
Discussion Starter #8
no drop in fuel pressure no smell of gas in oil i had replaced both O2 sensors on thing i notice and its seems to be consistent . If I crank engine over and over and the engine does not start ,if I then just bump starter the next try it starts right up on the freeze frame on my scanner it said spark advance 29 Does this have to do with ignition timing. I will have to get someone with a good scanner to check this for me I'll let everyone know what happens thanks for help
 
1 - 8 of 8 Posts
Top