crazy coolant temp reading and no power down low...

[WillWorkFoBoost]

Okay so I was driving my 87t home last night and after it gets up to temp It seems to not be able to get out of its own way down low... and in addition the coolant temp says its starting to over heat.... when I pop it into neutral to pull over the guage goes right back down to normal, then I put it back in gear and it goes back up and then its fine.. does this off and on while driving home as well as the down low hesitation... no check engine. I was thinking it must be something thats making it dump fuel down low because the coolant temp is on the fritz and i know theres many coolant temp and similar sensors that affect fueling...

If anyone can think of anything blatant that comes to mind by all means Id like to hear it.


Josh

 

[Failure14]

Check for codes is step number one.

If it keeps doing this, DONT drive it period.

Does it drive fine? Any power loss?

Does your oil have any milk residue?

Whats your oil pressure?

Check your coolant, is it full?
is it running out really fast?

I highly doubt its a sensor problem.

 

[lewis15498]

Dont drive it until you get it figured out and get yourself a real temp gauge. This forum doesnt need another BHG thread. The 7M is a great motor and gets a bad rap because its tempermental. Run it hot, and you may find yourself in the FS section looking for a new head. Usually those gauges are late to alert you, not early. If the temp gauge flutters alot check your connection to your temp sensor.

 

[WillWorkFoBoost]

It isnt a bhg I know that for a fact and I did state that it didnt throw a check engine. also it was not really overheating. I drove It a bunch today and it never did the collant guage thing it just has that hesitation and I think its throttle based, but Ive heard with tps sensors itll want to stall and this doesnt.. Im gonna throw on a spare coil pack and maybe a tps anyway and see if its better. I basically posted cuz of the guage going crazy and the hesitation at the same time but I believe now they are separate things. Was just looking to see if this was a distinct thing that anyone could pinpoint but otherwise im just gonna try some sensors and stuff that would make sense.
thanks
josh

 

[gaboonviper85]

Just because you don't have a check engine light doesn't mean you don't have codes....wonder why people just don't grasp this concept???!!

 

[WillWorkFoBoost]

My code scanner sure does grasp this concept.... as I said it has no cel codes.. look for newbs to pray on somewhere else.:aigo:

 

[toyotanos]

MK3 Supras don't use scanners, they use an older flash-code system. That is, unless you have an old Toyota scan tool with a DCL-1 connector.

Anyways, do the usual checks like coolant level, oil level, make sure your water pump is good, belt is tight, make sure the radiator isn't plugged (either way- coolant passageways or clogged fins), and make sure the sensor wires are all in good shape.

 

[WillWorkFoBoost]

Yes, I have a diag tool and it did not throw a check engine,( in the past when diagnosing different things this has worked great)It isnt a bhg. im pretty sure its an ignition thing and if not its a coolant temp/fuel thing.

 

[hvyman]

so where did you hook up your scan tool.

as stated before not all codes will even make the check engine light appear. you can have a code with out ever seeing the light.

try it this way.
http://cygnusx1.net/Supra/TechTips/engine_error_codes.aspx

a paper clip works good for me.

 

[WillWorkFoBoost]

The diagnostics port.

 

[WillWorkFoBoost]

Okay so I guess I should have posted my mods or my Iq level because I know how to check for codes and I know the 7m pretty well, as well as knowing cars in general pretty well. I guess I was just looking for supra gurus to point out something such as "the coil packs will cause that" or tps sensors go often". the cel has not blinked me any useful information. my mhg and arps are also not blown. All I wanted was basically the help of fellow 7m buddies to point me in the right direction of a bad sensor, and I definitely didnt ask for the noob test.

 

[Failure14]

Okay so I was driving my 87t home last night and after it gets up to temp It seems to not be able to get out of its own way down low... and in addition the coolant temp says its starting to over heat.... when I pop it into neutral to pull over the guage goes right back down to normal, then I put it back in gear and it goes back up and then its fine.. does this off and on while driving home as well as the down low hesitation... no check engine. I was thinking it must be something thats making it dump fuel down low because the coolant temp is on the fritz and i know theres many coolant temp and similar sensors that affect fueling...

If anyone can think of anything blatant that comes to mind by all means Id like to hear it.


Josh

My code scanner sure does grasp this concept.... as I said it has no cel codes.. look for newbs to pray on somewhere else.:aigo:

You never said you checked for codes, you said "no check engine",
that and "I checked for engine codes by TSRM and there were none" are a huge difference.

Okay so I guess I should have posted my mods or my Iq level because I know how to check for codes and I know the 7m pretty well, as well as knowing cars in general pretty well. I guess I was just looking for supra gurus to point out something such as "the coil packs will cause that" or tps sensors go often". the cel has not blinked me any useful information. my mhg and arps are also not blown. All I wanted was basically the help of fellow 7m buddies to point me in the right direction of a bad sensor, and I definitely didnt ask for the noob test.

Dude quit getting so offensive, we are just trying to help...

Not to mention, we are asking you questions and your not even answering them...

And if your so high on the fact of it being a bad sensor, CHANGE IT.
Simple as that, if you do not know how to change it, then ask us how to change it.

 

[jdub]

My code scanner sure does grasp this concept.... as I said it has no cel codes.. look for newbs to pray on somewhere else.:aigo:

Suggest you put down the scanner and follow the TSRM for checking codes - the after market scanners to not always work on the 7M. Toyota made a scanner for the engine, but they are rare.
Using a scanner looks like a newb to me Might want to drop the attitude if you want any help from the guys that know this car.

I would check your timing, assuming there are no codes. I would also take an IR temp gun and check for cold spots on the radiator that would indicate clogged coolant channels. Check the fan clutch as well.

 

[WillWorkFoBoost]

Look, all I was saying is I dont have a bhg, my car was not really overheating im sure of that so I guess thats probably a finicky coolant temp sensor, because I checked and it wasnt any hotter than usual, my rad isnt clogged, its an aluminum one and its new, Its safe to say that theyre separate instances. my code reader does the same thing it causes your cel to blink via plugging it into the diagnostics port and you count the blinks and look in the book. as I said It has worked fine in the past. as for getting Defensive, Its hard not to with the way people jump down your throats.I guess its just swap coilpacks, cps, tps maybe? I guess I shouldnt have posted and the only reason I did so is because of the coolant guage but It did that once and it was very cold and upon driving the car the next day it never happened again. so sorry the actual problem is just the hesitation at low throttle/rpm.

 

[WillWorkFoBoost]

Okay so today it finally threw code 21, which as far as my book says is o2 signal. it still is bogging down low.. I threw a spare o2 on and it made no difference. it seems to run fine until about 15-20 mins into a drive consistently, well after its warmed up. problem is the book lists tons of things under that code that could be culprit.

thanks,
Josh

 

[lewis15498]

For the record running hot is not gonna throw a CEL and if your temp gauge isnt accurate or operating properly, you have no way of knowing if your engine is overheating until its too late and you have no basis for saying it definitely wasnt overheating. I did tell you to check the connection on your coolant temp sensors. If you computer thinks the engine is cold it will add extra fuel which can cause a rich condition and slight loss of power if its not really cold. You got some newb answers because its typical for newbs to insist that there shit isnt overheating or BHGd. Your a new member here and we have no way of knowing what experience you have. Your attitude is not going to encourage anyone to help you.

 

[WillWorkFoBoost]

Okay so I said that it threw code 21... and i know what a car does when it overheats and it wasnt overheating. also I put the whole thing back together like 1500 miles ago with the head checked and decked and a hks mhg and arp headstuds, and it doesnt run hot and it doesnt consume coolant nor is there oil in coolant or coolant in the oil. I would say that Its more likely that is something less severe than a blown metal headgasket at 10 psi.....

 

[Failure14]

Okay so I said that it threw code 21... and i know what a car does when it overheats and it wasnt overheating. also I put the whole thing back together like 1500 miles ago with the head checked and decked and a hks mhg and arp headstuds, and it doesnt run hot and it doesnt consume coolant nor is there oil in coolant or coolant in the oil. I would say that Its more likely that is something less severe than a blown metal headgasket at 10 psi.....

After it threw the code 21 and you put on a spare o2 did you check for codes again or no?

Cause it could be the wireing to the o2 which is done with and your ecu cant read anything so its just
throwing random ratios of air/fuel, thats really my only thought other than your other sensors are done with.

 

[JesseH]

Have you tried calibrating your TPS?

How does your power level feel under boost? normally if your coilpacks are weak/bad you will start to get a hickup or miss under boost.

As far as the temp gauge goes, trace the wire, if it is cut or exposed anywhere and hits ground it will cause the gauge to go to red. If you have a few extra bucks I would replace the sensor just to rule that out, they're only 12.99 IIRC.

 

[WillWorkFoBoost]

well correct me if im wrong but the o2 signal doesnt necesarily mean o2 failure, in my book under that it lists actually alot of things that would make that code, the o2 is just reading that the afrs arent right... the book is actually pretty vague and lists ignition stuff, fuel stuff and so fourth. anything that would cause it to get a funky afr... it lists plugs, wires, ignition wiring or coils etc as well as o2 and injectors.... pretty general but Im gonna try a cam position sensor tomorrow and if that doesnt do it it could be the ignitor chip. It really feels like an ignition deal, misses at idle after its warm and hesitates/bogs until you give it some throttle. then it smooths out.