mdenz3

I would suspect your OPTI, because its reading spike rpms of upto 6375, but with the mass air and map readings for alot lower RPM. Also the transmission rpms don't match the engine and seem correct. Also i think you right O2 is going bad.

bubba24

alright I hope not but the opti is just new and put in on January. But there is no code for a low/high pulse. but if it was the opti then it is a heat issue i guess for the optical part. Still dont know why though the tps is unplugged it will stop but just hold at 1500 rpm about wont surge. But thanks I will check all the stuff u pointed out there

thanks for the help

mdenz3

When the the TPS is unplugged it goes into a sort of fail safe mode and opens the IAC to about 100-130 counts. Where did you get the replacement opti from?

bubba24

i bought that accel optispark jcwhitney. Works great unless it is screwed now then perhaps it worked good haha. But when i first put it in felt like a new car. but......now i dunno


but one thing is it wont surge while in drive it just idles higher dont need the gas all that much to drive. Then put into park and bam surging like crazy. Also anything under the car that may have screwed up from water or snow buildup from being low ground clearance. Here it is just starting to melt outside, and I got hung up once at a end of a backalley on snow. Seems as though after all that it has ran like crap. Maybe coincidence i dunno

another thing is too that as it warms up the iac drops to zero. After the zero the tech needle starts its twitching and then starts the revving or surging.

bubba24

okay after fooling around and trying to find this problem I looked to erase the codes I placed after unplugging the maf and tps. Now i got this code again whih i had long ago when I replaced the opti in january. Code 41 est open. Now what exactly is this and where on the engine? Most likely opti right?? This is probably causing the engine to do its surging and tach twitching at idle when warm not cold.

mdenz3

according to what i can find at this site:
http://www.montecarloss.com/SSThunder/gmcodes.html
Yup Opti isn't sending the RPM signel to the ECM. You said you bought it not that long ago it would be worth checking into a possible warrenty, if they say no theres always the call Accel and whine and what not to hope they replace it for free.

bubba24

yep it was the opti, but I took the air compressor and blew just a small amount of air through the vents and it cleared right up for a few minutes then it went haywire again and started missing and surging high idle deal.


Now I thought maybe compressed air like you use for computers in houses myabe I could use that to blow it since it is a dry air. Or is there something else I can use, or possible the opti is still shot and blowing air just fixes it for a few minutes.

bubba24

okay sorry for bugging about this so much....


But figure this out tonight it was about +3 OUTSIDE TEMP and the car ran perfect, even tried to get it to surge or high idle and nothing. Car was warmed to operating temp. But this afternoon doing the same thing except I actually had problems with the high idle and boucing tach. Staying steady at 2000. But it was +10 OUTSIDE TEMP. Im sure if the opti was hooched it should have done it eithier way right? So maybe something relating to temp im thinking. I have never fought with something this annoying in my life. lol

thanks for the help

Dave1980

intermitant problems suck. Opti is known for that. I have not heard good things about the accel opti on the forums. If you have the money then I would go with a deltec.

ashakeandfrys

I have a similar problem, but I think the opti can be taken out of the possible problems, as the rev is not erratic; it's smooth. and, since it does not seem to carry throughout the "band" of the tach, it may just be faulty wiring somewhere.. possibly to the pcm? I haven't had much time to look over any of the wiring, since I just "un-cocooned" the Z.

Also, when it revvs, can you hear it try to suck air through the small IAC passage? I hear that on mine, and it seems that the IAC does not open because the PCM expects the engine to be running at a normal idle..

hopefully this helps a little bit

bubba24

yah you are exactly right ashakeandfrys maybe the opti isnt to blame but wiring, also yah i hear it sucking air too. But ive been looking so sometime I will figure it out.

drpz28

have you replaced your coolant temp sensor? my car would start surging at idle and go up to 3k a few times and die, it wasnt giving any codes either.
i called a local shop and they told me to replace the coolant temp sensor.i did and it runs great now

bubba24

yah I fixed that coolant temp sensor, but it seems like once it gets to almost the 200 c mark on the temp guage in the car it will do it then. Or in any other car it be pretty close to the middle mark on the temp gauge. then after that it will surg and stay steady at 2000 rpm

bubba24

Okay I never knew that on datamaster that when you print out a record it actually shows more info. Like for example iac tgt. On the screen it only has iac counts. Well Ive been finding out by printing out records to see the iac tgt is messed. Counts are at 160 when tgt is at 32. Other times count at 4 tgt at 10. 0 counts and 28 tgt. Bought new iac....... what else controls the iac or tells the pcm to control the iac differently?

ashakeandfrys

tgt?