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scorpiio1971

Idle issue after partial rebuild

Question

 Hello everyone! I purchased a 2000 Grand Am with #1 spun rod bearing. I installed new crankshaft, new rod and main bearings, new oil pump, new water pump and timing components. Flushed all oil passages removed cam housings and lifters to flush out any metal shavings.Lubed and installed lifters and cams back to original positions. When i started it for first time it ran very rough for few seconds then smoothed out then i realized i had a leak from the water pump. That was my fault for not following the correct install procedure. Fixed that issue then restart ran smooth for short time then engine rpm's started to rise then fall sometimes shutting down all together. It restarted everytime but didnt clear up. I also have a 99 Grand Am that has three spun bearings i plan on rebuilding so i removed throttle body and installed it. Checked all vac lines all good restarted runs better but if i bring up rpm's and let off throttle the rpm's climb a little and doesnt want to return to normal idle rpm's. i noticed throttle cable is a bit sloppy at the throttle body but seems to return fine so i guess what im asking does this sound like a throttle position sensor problem?  I did replace crank sensor but did not replace cam sensor.  Any help would be greatly appretiated

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Update now the car starts up idles smooth at a 1000 rpm's for a min or so then drops to 500 rpm's idles rough then dies.

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Are you 100% Sure that you don't have a vacum leak somewhere ?..Around the Intake manifold possibly....Sometimes vacum leaks can be hard to find...

Edited by TWO LANE BLACK TOP

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I can't say for 100% but I have checked all possibilities that I am aware of. I did a multimeter test on the TPS sensor just a hour ago and it passed with flying colors. Only thing I can think of now is to switch out IAC valve. Im taking one from the other 2.4 I have waiting for a rebuild. Any other possibilities you can think of? What's the best way to confirm there is no vacuum leaks? Thanks for the feed back! 

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There are a few different ways to check for vacum leaks..the best way is to use a smoke generating machine...But if you are like me...And don't really have access to one for free...I usually use brake clean in a squirt bottle..with the engine running..I spray around all the lines..around throttle body..intake manifold..power brake booster..Around the fuel injectors anywhere there is a gasket or hose connection..ETC..Listen for subtle changes in the way the engine idols..some People do the same thing with trans fluid or WD-40 and look for smoke to come out of the exhaust...It is effective but can be really messy..When the idol changes.. Or smoke comes out the exhaust..Note the area where you were spraying..Will more than likely be the source of the vacum leak..As far as the Idol Air Control sometimes.You can clean them out real good with carb cleaner and get them to work correctly but that Can be hit or miss...One other thing is the fuel pressure regulator or an extremely clogged fuel filter...Although those would be extreme longshots....and very unlikely but not 100% impossible....

Please let us know what happens....

Edited by TWO LANE BLACK TOP

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Thank you for the info! I'm heading out to my garage soon I will update as soon as I get finished. I did remove the IAC valve last night and cleaned it and the passage that the air flows through. They were pretty dirty and the rubber O-ring had been damaged and it was pushed to the very back of the IAC so not sure how much that will effect it but we will find out soon. I didn't have time last night to start her up. Ok off to garage will have feed back after while! Thanks again

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OK I forgot to mention earlier I had used the IAC valve off the other motor and car would not start at all. Cleaned the original IAC and installed still doing the samething. I thought I had carb/choke cleaner but was all out. I did pull plugs they were brand new and they are black as coal. Definitely running rich!  So while I had them out I did a compression test #1 150 #2 160 #3 155 #4 150 pretty happy with that considering I didn't replace pistons and rings that have 170,000 on them.  I have check engine light but no scanner so I'm going to buy one tomorrow along with carb/choke cleaner. I will check in as soon as I pull codes and check for vacuum leaks. 

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OK this is were I stand. Pulled codes 7 total all to do with transmission! The rookie that I am forgot to plug in the harness that goes to bellhousing. Now that is taken care of I have no check engine light but still have issues. Friend of mine that turns wrenches for a living said it sounded like a fuel pressure regulator. I know my other Grand am before the spun bearings issue idled like a dream so I pulled fuel regulator and installed. This created a new problem. I now have fuel spraying out of the bottom of the regulator from the return fuel line. This is were I get very frustrated is there supposed to be a rubber oring on the return line? I don't remember seeing one on either regulator. If one is supposed to be there does it slide over the return line or does it go down into the regulator. Nothin worse than gutting a engine for the first time and putting it back together and dealing with this sort of issue. I know it's something simple! By the way Thanks for the suggestion so far! 

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Without actually seeing it.. Would be hard for me to say for sure about an O ring...Or where it Would go....Has been awhile..Maybe if I could see some detailed photos..

You're Welcome..No problem

Edited by TWO LANE BLACK TOP

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I can't do vacuum leak test cause it is running so poorly. I resolved the rubber o-ring problem one thing I noticed is when the fuel pump primes the system it runs way longer than I've ever heard one run before. I have a 99 Grand am I've been driving for over a year and it primed for just a few seconds. This one probably runs for 10 seconds or more. I have checked for leaks none found. I don't know much about fuel pumps can they leak within themselves causing it to run longer to prime system. I have fuel pressure tester but don't have the stuff to connect to fuel line. I don't understand why they didn't put a quick connection in line. 

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I added a couple pics of the scanner data. It showed the code p0480 and don't remember other number but it said cooling temp sensor the p0480 is #1 fan but I noticed that fuel system 1 has OL can't find a reference for that my thought was Off Line. Also the STFT & LTFT are also part of the fuel system and they are at zero. Are you familiar with any of this info. It may mean nothing I am not familiar with these scanners at all. Thanks for any help

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STFT= short term fuel trim

LTFT= long term fuel trim

OL= open loop which means that when the engine is cold the MAF (Mass Airflow sensor) and the Oxygen sensors are not talking to each other and is running on the factory cold start parameters.. (rich)..that are stored in the PCM (Power control module) As the engine warms up it goes into closed loop..Which is where the coolant temp sensor comes into the picture... When it senses the proper temp..It tells the PCM.... Then the MAF and the O2 sensors actually start communicating..Adjusting timing..fuel mixture (leaner or richer) fuel Injecter pulse width...ETC..According to the throttle position..Temp..humidity and driving conditions...ETC....That is also why a vacum leak can cause it to idle up and down..When extra air is introduced into the system between the MAF..and the O2..It sends the PCM a confusing signal so it  idols up and down to try and compensate...for the extra air...

Also when the check engine light is on it sends it into open loop...(rich condition)...

The fuel trim is basically what the mixture of air and fuel is over different time periods.... 

Edited by TWO LANE BLACK TOP

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That's great feed back I appreciate the info! I'm mechanically inclined but when it comes to all this computer stuff I'm a bit behind the times. After I finished the engine I installed new Bosch plugs thinking they are new I didn't think they could be a issue. Friend came out to help me and he could hear what he thought was spark arching so I removed cover and sure enough #1 plug was cracked in half. Put in a old one and it started and idled a lot better. I'm going to pick up a new set of NGK plugs tomorrow. I have heard this engine is picky about plugs. What's your thinking on this? NGK double platinum? 

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It's funny how you get tunnel vision when trying to solve a running problem. It took all of 5 min for my friend to resolve my problem. What have I learned from this? Take a step back and start with the basics. I found that three of the four Bosch plugs I bought were defective. The ceramic piece was loose and apparently causing spark to arch. I've heard a lot of bad things about Bosch plugs now that I have experienced them I think I will stay away from them! TWO LANE BLACK TOP I truly appreciate the impute. I'm happy to say the car had its first test drive tonight and ran great! I forgot to mention that I had also failed to reconnect the temp sensor and from your info on the scanner readings that would have also caused some issues and thanks to that info made me check the temp sensor! Thanks again! 

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So what plugs did you replace the Bosch plugs with? NGK? AC Delco? Champion? E3?

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I went with NGK Platinum G-Power 

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Thank you for the kind words....Glad was able to help....

Edited by TWO LANE BLACK TOP

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