little rough idle with a misfire sound

**Yourbeat** · 06-27-2012, 08:58 AM

2000 trans am ls1 m6
Muffler delete k&n cold air myers short shifter are the only miss to the car.

Hey guys, so I just got my car back a couple weeks ago the warranty company put a newer motor in it bc the last one had a rod knock. Since I got it back a week after I noticed that it idles a little rough and makes a pretty consistant misfire put put sound at idle. The biggest issue is that it seems to bog out in low rpms and then it bucks a little bit. It did have the ses light on the other day which said IAC code and lean bank 1&2. I deleted the codes and they havnt cone back yet but the car still idles rough with the puttering sound and still boggs out when I go into first or let second come to low and then try moving. Any help with this would be appreciated.

***SMWS6TA*** · 06-27-2012, 09:11 AM

Lose the K&N filter and get a can of MAF cleaner to clean your MAF

**Knight** · 06-27-2012, 09:17 AM

Agree with Scott. I'd also do a once over and make sure everything is good - spark plug wires are tight, no vacuum leaks, ect.

***SMWS6TA*** · 06-27-2012, 10:06 AM

The shop that did the swap could have missed something like Walt said do a once over.

**Yourbeat** · 06-27-2012, 11:35 AM

i just cleaned the MAF the other day with the cnc maf cleaner. i have pushed all the plugs and wires to make sure they were connected as best as i could considering i have huge hands and cant really fit in there to well. ill have to try checking everything out. im so new to these cars that even if i give it a once over i would probably still miss things myself.

**Naaman** · 06-28-2012, 12:45 PM

I can relate to your problem. I've had IAC problems as well as MAF problems before. Both were simple fixes:

The MAF problem happened after I installed an SLP lid. The little foam piece that seals it got sucked up into the MAF and was blocking airflow. I could not get the engine to rev past 4000... it would just bog down to 3000. Took me a while to figure out. While trying to diagnose this, I was directed to the spark plugs and wires (as the symptom developed aftery lightly spraying the engine bay during a car wash).

I took off the wires and sprayed wire dryer on them and on the plugs. However, when I put the wires back on, I did not snap them in all the way (same problem... just could not reach in there with my hands; the number 2 wire and number 6 wire were the main culprits). I did not know this at first, because the connection was intermittant. I was getting subtle misfires, as some of the time, I was running on six cylinders. I noticed during a plug and wire change that my number 6 wire was toast and my number 2 wire was really loose.

Upon replacement of the plugs/wires, my car was running much smoother.

As for my IAC, when I did a throttle body swap, I guess I damaged the o-ring for the IAC valve, because I could not get it to idle properly (I tried adjusting the set screw several times, but still, the problem kept coming back). After a while I took it all back apart and noticed the broken o-ring. I bought a replacemnt part from O'Reilley's and problem solved.

Anyway, if you're not absolutely sure that those wires are hooked up right, I'd get that squared away before putting any money into it.

**blackcamarob4c** · 07-03-2012, 02:53 PM

Mine was doing the EXACT same thing. I pulled the plugs and what did I see? # 5 was cracked enough to cause this miss. Changed the plug and runs great

**Yourbeat** · 07-04-2012, 10:48 PM

i checked all plugs and wires, the shop reused the plugs and wires from the old motor, which was ok because i just put new wires and plugs in right before the motor went. everything is connected tight. i took the MAF again, and it seems to be 100% clean and clear. i checked all injectors and they seem to be working perfectly. im thinking it is something as simple as a fuel filter, im pretty sure its the original filter. sometimes the car drives great sometimes it acts up. im going to change the filter this weekend and hopefully something that simple clears it up. i do need to look more into why its throwing the IAC code though.

***SMWS6TA*** · 07-05-2012, 07:47 AM

After you change the filter get a fuel pressure gauge form any parts store (usually around $20). That a reading form the fuel rails.

At idle it should be around 45-55 psi.
Can't remember what it is when you turn key forward one click but do not start. Sorry but post what you find.

Now if you notice that the pressure is dropping while in this mode then you need to check the fuel pump.

**Y2KArcticSS** · 07-05-2012, 10:04 AM

If none of these solve your problem, also look into the catalytic converters, if you have any. I ran lean codes quite often when mine started to go bad. I didn't even get rear o2 codes until further into the problem. I had just passed the extended warranty GM put out for cats (10 yr-120,000 mi), so I just put headers on and deleted cats. Just another suggestion

**Yourbeat** · 07-05-2012, 02:04 PM

well headers are in the immediate future, i think my buddy has the fuel pres gauge so i can prob have a number for you after i do the filter this weekend. as far as cats go im not sure if im going catted Y pipe or no cats yet.

**2002ssslp** · 07-05-2012, 02:45 PM

Originally Posted by Yourbeat

2000 trans am ls1 m6
Muffler delete k&n cold air myers short shifter are the only miss to the car.

Hey guys, so I just got my car back a couple weeks ago the warranty company put a newer motor in it bc the last one had a rod knock. Since I got it back a week after I noticed that it idles a little rough and makes a pretty consistant misfire put put sound at idle. The biggest issue is that it seems to bog out in low rpms and then it bucks a little bit. It did have the ses light on the other day which said IAC code and lean bank 1&2. I deleted the codes and they havnt cone back yet but the car still idles rough with the puttering sound and still boggs out when I go into first or let second come to low and then try moving. Any help with this would be appreciated.

I work for a warranty company in PA. Which one did you use and how did they treat you.

**Yourbeat** · 07-05-2012, 04:23 PM

continental warranty i believe they are based out of Delaware? the communication with them sucked! the only good thing out of the experience was that after 4-5 weeks i finally got my car back with a running motor. but then they had hidden fees they didnt cover so it cost me about 500$ which was only supposed to be a 100$ deductible...

**2002ssslp** · 07-06-2012, 05:33 AM

Originally Posted by Yourbeat

continental warranty i believe they are based out of Delaware? the communication with them sucked! the only good thing out of the experience was that after 4-5 weeks i finally got my car back with a running motor. but then they had hidden fees they didnt cover so it cost me about 500$ which was only supposed to be a 100$ deductible...

Not uncommon with aftermarket warranty companies.

**Yourbeat** · 07-07-2012, 03:50 AM

either way i didnty have to foot the whole bill for the motor and the install. but the issue now is i feel like the motor swap is one of them domino affect type things where now every little thing will go wrong one after another. thats all i keep thinking about so im trying to get ahead of all the issues and update all the little things now before they go bad. im going to be doing all the fluids soon, coolant flush, trans fluid, dif fluid. i would like to do the drill mod soon too and seafoam everything to try and have everything nice and new and clean.

**Yourbeat** · 07-07-2012, 03:54 AM

i realize these things are routine maintenance but im pretty sure the previous owner didn't keep up on any of these things considering at 79k when i bought the car the wires and plugs were just about shot and the original plugs. so the hopes that he kept up on trans/ dif fluid fuel filter etc seems out of the question. im hoping that after saving my money for years to buy my dream car i didn't buy a turd....