idle woes after engine install

[jadonP5]

Hoping someone may have had a similar experience....I just had a used (only 3k miles) engine put in my car due to my original going bye-bye. The car has a high idle- 1000-2000 and when I am decelerating or coasting idle surges and bounces all over in the 1000-2000 range. As soon as I hit the accelerator or brake more firmly, it stops. It's like it can't decide whether or not to downshift. It's also throwing a CEL due to idle. The guy who installed the motor told me to drive it a while and see if the ECU would relearn. He said if it didn't take it to Mazda to have them program the idle.

I already tried clearing the ecu and relearning based on this forum's preferred method of doing so- battery, pump brakes, restart, let idle- with NO results.

I was just curious if anyone who has put a new or used engine in has experienced this situation, since I am wary of taking it to the dealer. I've already been without my car for a couple weeks and am out a whole crapload of money, so I want to avoid any of this if possible. If I do take it in, does anyone know how much they would charge me to reflash or reprogram the ECU?

Thanks for any info.

[wipedawg]

usually for a reflash its in the area of 75-100

[boostisgood]

did he change the ECU or just drop in the engine ? IT sounds to me like you have a possible vac leak.

Take a spray can of brake cleaner, and spray around your vac likes, when the RPMS change (RPMS will go slightly higher) you have found your vac leak.

Other then that, it could also be a sensor, take it to a parts store (pep boys charges but autozone does not) to pull the code.

[boostisgood]

BTW, you cant reset the PCM when it has a CEL by disconnecting the Batt.

[geomatics_tech]

throttle position sensor maybe, get your codes checked and cleared.

shaun (canada)

[mogi]

might want to make sure your EGR isn't stuck open as well...
(check the howto section)

[boostisgood]

Werd to the last 2 posts. :D Get the code (s) checked first, then go from there.

[kcbhiw]

Vacuum leak is my bet. Check all of the small hoses.

[SlowPro98]

I just had the engine wobble issue last week. Check the vaccume lines on the throttle body. if that doesn't fix it, check out the how-to for the EGR.

[SkinnyJoint]

i would first get it checked to see what code(s) are thrown, and possibly maf could be fucked up....

and wtf is PCM

[jadonP5]

pcm=powertrain control module

thanks for all the suggestions...on my way to see if I can get someone to pull the code for me...autozone is too far away!

tony

[SkinnyJoint]

and can someoen give me a quick class on PCM 101

[jadonP5]

and the verdict-

2 codes thrown- P0106-MAP/Baro Circuit Performance
P0507-Idle Control System- RPM Too High

#2 likely being caused by #1.

Following excerpt from shop manual-
"PCM monitors differences between intake manifold vacuum and atmospheric pressure at idle, which EGR
boost sensor detects by switching EGR boost sensor solenoid. If difference is below 6.43 kPa {48.2
mmHg, 1.90 inHg}, PCM determines that there is EGR boost sensor performance problem.
Diagnostic support note
• This is a continuous monitor (CCM).
• MIL illuminates if PCM detects the above malfunction condition in two consecutive drive cycles.
• PENDING CODE is available if PCM detects the above malfunction condition during first drive cycle.
• FREEZE FRAME DATA is available.
• DTC is stored in PCM memory.
• EGR boost sensor malfunction or substandard performance
• EGR boost sensor solenoid malfunction
• Loose, damaged, misconnected, clogged or frozen moisture in vacuum hose from EGR boost sensor
solenoid to EGR boost sensor
• PCM malfunction
• Loose, damaged, misconnected, clogged or frozen moisture in vacuum hose from EGR boost sensor
solenoid to EGR valve"

Going to take it in tomorrow so we can swap out sensors, etc and see what gives.

[mogi]

make sure all your hoses are hooked up properly :)
wouldn't hurt to check for vac leaks like described earlier

[SkinnyJoint]

hey thx for that post man

[jadonP5]

ok...swapped out new egr valve for my old one and new iac valve for my old one and the car is running perfect. it was a bad egr, and changed the iac too just for good measure. too bad now when I was driving it around checking out everything it feels like I have a wheel bearing on the way out...!!! And to think I bought this car to have something more reliable! :)