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so i was having a problem in which i though my Shiftplus was stuck on. as it turns out i forgot to reconnect my IAT Sensor and that turned out to be the issue. can anyone shed light on this, as to why IAT's would affect the tranny?
aaaaah
okay then
that explains it....also explains the crappy gas mileage i guess
Same thing happend to mine, couldnt find the problem in forever, turned out my IAT was broke
~2014 New Z under the knife, same heart different body~
______________________
WHITECAVY no more
2012 numbers - 4SPD AUTOMATIC!!
328 HP
306 TQ
I originally thought my shift plus was dead, but it was just the damn IAT sensor.
PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO
glad to see it wasnt just me lol
No.. a slipping transmission would be the cause of that.
Bad IAT just commands full line pressure. It'll shift hard.. but not cause slip.
sndsgood wrote:would a bad iat cause your car to slip out of gear at 20-30mph consistantly?
Oooh, please put a built transmission into the fire. It would be like a perfectly erect pencil-eraser nipple on a perfect tit. Sorry, I'm drooling.
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"The J's weren't designed to be sports cars, the suspension sucks, the brakes are tiny, and the target market for our car doesn't need to be able to do any more than 65mph." - Shifted
A more accurate observation has never been typed. These should be the starting points before any serious performance modification. What's the point of making a serious performer if you can't control it's power?
^^^^^^ wtf LOL
Why did they program a bad IAT to send the car into limp mode for? Thats seems a little overkill to me..... It must just be an Eco thing thank god.... my LD9 doesnt care.
Weebel wrote:^^^^^^ wtf LOL
Why did they program a bad IAT to send the car into limp mode for? Thats seems a little overkill to me..... It must just be an Eco thing thank god.... my LD9 doesnt care.
Nope, IAT and ECT are two vital sensors in determining Spark timing. This happens on all GM's and most every car out there. When the PCM senses a problem and all drive cycle criteria are met to run the comprehensive component monitor it will set a pending code, and freeze all adaptive shift strategies for the transmission as well as command full line pressure. (this is done so if there is an issue with the trans itself instead of just engine management it will save the transmission clutch packs from damage do to overslipping)
Buildin' n' Boostin for 08' - Alex Richards
I dont have an automatic... but I drove my 2.4 with the sensor unplugged before... and didnt notice a difference in the way the engine ran..... I guess closed and open loop, and LHM feel the same with a manual.
Thats prob why I've always thought it didnt really do anything.
Alex Richards wrote:Weebel wrote:^^^^^^ wtf LOL
Why did they program a bad IAT to send the car into limp mode for? Thats seems a little overkill to me..... It must just be an Eco thing thank god.... my LD9 doesnt care.
Nope, IAT and ECT are two vital sensors in determining Spark timing. This happens on all GM's and most every car out there. When the PCM senses a problem and all drive cycle criteria are met to run the comprehensive component monitor it will set a pending code, and freeze all adaptive shift strategies for the transmission as well as command full line pressure. (this is done so if there is an issue with the trans itself instead of just engine management it will save the transmission clutch packs from damage do to overslipping)
Insightful info. I wonder what happens if you live in a constantly less than -40 climate? lol I know certain cars will calculate IAT based on ECT and other factors. It shows up on scan tools pretty accurately.
Listen F***ers. FASTERTHANAHONDA is a joke because I WORK FOR HONDA. I'll talk @!#$ about Fords to, that doesn't mean I can beat a 12 second mustang.
FasterthanaHonda wrote:
Insightful info. I wonder what happens if you live in a constantly less than -40 climate? lol I know certain cars will calculate IAT based on ECT and other factors. It shows up on scan tools pretty accurately.
Name a car that actually starts and runs in a -40 climate....
More fun facts, the PCM recognizes a problem with the IAT or ECT circuits and sensors via the logic bridge immediately after the key is cycled on. If the ECT and IAT are not within 11 degrees of each other after a cold soak (8hrs) then the PCM sets a pending code for whichever is furthest from logical explanation. I.E. if the engine has been running for 10 mins and the ECT is unactive and stuck at 35 degrees it will set the code for ECT sensor circuit malfunction.
Or if the IAT is reading -40 and the ECT reads 90 the PCM assumes (through virtue of the engineers) that the ECT is correct since the IAT is closer to the extreme low value.
Buildin' n' Boostin for 08' - Alex Richards
A cavalier will start and run in 40 below weather if it had a battery blanket on it....... but wou'll want to wait awhile before you try to drive it..
Weebel wrote:A cavalier will start and run in 40 below weather if it had a battery blanket on it....... but wou'll want to wait awhile before you try to drive it..
A battery blanket isn't as vital as a block heater for the -40 starts. It hits those temperatures a couple times a winter here. I've been driving down the highway with my laptop scanning and seen a consistent temperature of -37C on the IAT in the middle of the afternoon. The car runs fine but really sucks the fuel due to the dense air.
^^^^^ ya.... in those temperatures I would want to have both..... a block heater so the engine doesnt freeze, and a blanket so the thing will actually start.
This is OT but when I was stationed in Anchorage and I still had my 93 Sunbird (2.0L with 5-speed) it got down to 40 below sometimes at night and I didnt have a plugin on the car of any kind.... As as long as it was drivin every day..... It fired up and ran in those temperatures every time... although barely sometimes...
It surprised the hell out of me.
I have a question,
My car will be driving fine, idling at 600rpm as usual at a stoplight, stopsign ect.
Then all the sudden idle will jump to 1000rpm and the "traction control off" will turn on, it drives like normal, cept for the annoying high idle and annoying light.
anything to do with the IAT perhaps?
CLC wrote:I have a question,
My car will be driving fine, idling at 600rpm as usual at a stoplight, stopsign ect.
Then all the sudden idle will jump to 1000rpm and the "traction control off" will turn on, it drives like normal, cept for the annoying high idle and annoying light.
anything to do with the IAT perhaps?
Pretty much anything related to powertrain management will put the vehicle into limp home mode. Usually you have different degrees of failure and limp modes that the PCM will try and initiate based on the severity of the failure and the severity of the potential failures that could result.
I.E. If the 1-2 shift seems sluggish to the PCM (>300Ms to actually see the shift occur) and the adaptives run to their high limit a P1811 is issued (Max Adaptives reached) and is generally accompanied by a P0730 which is improper gear ratio.
Of course this calculation is just that, a calculation and for the most part anything that occurs between the turbine shaft speed sensor and the VSS including any slop or misalignment can cause this. But it cannot decipher between a simple wiring or sensor issue and a physical failure in the transmission, it just sees it as a serious fault, defualts to limp home mode which commands max line pressure to keep any good clutches from slipping and overheating, thereby saving the transmission and freaking out the customer.
Its really quite simple and a very ingenius way to save the car, but in most cases the customer is pissed off cause they think the symtoms that they feel in the trans shifting hard is bad for it. In reality the car is actually saving itself...making it smarter than the person behind the wheel.
Buildin' n' Boostin for 08' - Alex Richards
^^^^^ that really didnt answer his question LOL
Does your ABS light or parking brake light come on when this happens? Could be a wheel speed sensor malfunction.
And 600rpm seems a little low for an idle to me.
600 is what the car has always idled at.
As far as other lights.
The abs light went crazy on and off as well as the traction control light for a couple of weeks after I dyno'd the car back in October.
Eventually the abs light stopped popping on.
The traction control light has come on and off every day or so for a couple weeks, then taken a break for a while, then the pattern would start again.
The tech at the dyno told me in case that happened, just have somebody with a nice scanner reset the traction control and it would be fine.
but the thing is, back in the fall after I dyno'd it, it was not driving any differently and the idle did not change, this has only started within the last few months.
Back to what Alex was talking about,
Do you think this is the cars way of telling me that my clutch packs are going bad, or maybe the T/C?
It reads that one or the other is malfunctioning therefor it goes into limp mode?
Idle is engine performance issue, Honestly if the PCM recognizes something is wrong it needs to be resolved before any further testing is done. What its sounds like to me is that you need to go through and get a vacuum gauge or a scanner that can graph live data and get a good idea if anything looks out of order. If your MAP value is high at idle you may have a vaccum leak somewhere...So check the basics first and make sure its nothing obvious.
At least pull some codes, descriptions of what it does over the internet are bitches to diagnose...
As for your TC or clutch packs being on the south side of no where...
PCM has no physical way of telling if the torque converter is bad, physically there is a calculate value based on engine RPM and turbine shaft RPM that it gets its TCC lockup/slip data from on our PWM TCC's. But otherwise a TC or a clutch going south is RARELY ever a problem these days because adaptives and shift quality overall is all kept well in check.
Buildin' n' Boostin for 08' - Alex Richards
I might have to just call my buddy up and have him check it out with the TECH II.
That will find out what's going on shouldn't it?
As far as checking obvious things, What are some normal places to encounter vacuum leaks on eco's?
IDK where normal places for them to leak would be other than on the brake booster hose.... but a Trick I used to use was to spray the lines with starting fluid and listen for and abrupt changes in the idle... if theres a decent leak... the fluid will be sucked into the hose and through the throttle body and make the idle jump around. It makes finding leaks easier..... but sometimes you still have to just check them all by hand.
Hello All,
Honestly if the PCM recognizes something is wrong it needs to be resolved before any further testing is done. What its sounds like to me is that you need to go through and get a vacuum gauge or a scanner that can graph live data and get a good idea if anything looks out of order. If your MAP value is high at idle you may have a vaccum leak somewhere...So check the basics first and make sure its nothing obvious.
Parking Sensor
