UPDATE...Check My latest post

I'm asking because the car has been traping like 5 mph lower than usual and I think its a rich condition after my headgasket/wp swamp. On my new waterpump the temp sensor wouldnt screw in all the way for whatever reason, so I just let it go in half way since I was afraid of stripping it out (got real hard to screw in any further). It's wierd because it goes right in/out on my old pump. Is it possible for this to cause the car to run rich? I belive the rich condition is what is costing power because my mpg is not where its suppose to be either...its lower than after the head gasket change/full tuneup.

There are no codes from the pcm about the sensor, my temp sensor which is in the head reads correctly.

Now the big question would not having the temp sensor completely flush (all threads inside) w/ the waterpump housing cause a lower than normal temp reading? I'm afraid to yank it out yet and lose all that coolant for the 3rd freeking time. Also does the car even use readings from the temp sensor at WOT? Would this problem even effect 1/4?

Would getting a data logger help diagnoise if its my temp sensor, such as being able to monitor the reading?

BTW: The car runs and idles just fine....seems perfectly normal except for the mpg and the 5 mph lower trap. (First time to track and it ran 99mph) would this problem even be able to effect WOT?

 

Would that sensor not being all the way in (its probably 60% in) really read that much of a lower temp to make a 5mph diff?

 

Because the sensor has tapered threads, it generally should not be threaded in all the way, anyway. It should work fine as long as it is exposed to coolant (which it is). If you are concerned about what temps it might be sending to the PCM, scan or datalog it.

 

Do you have any exhuast leaks from removing and placing the heads?

 

Is it possible you damaged the sensor? If its showing a very low temperature, it can prevent the PCM from going into closed loop, and if its reading really low, it can cause the engine to run with cold-start enrichement, causing a very rich A/F ratio.

Check the sensor, using the resistance vs. temp data shown on Shoebox's website.

 

What do you mean exhaust leaks? From the headers? or the actual head?

 

Well last night I discovered my fans no longer come on at all and the PCM is programmed for them to come on sooner. Around 210 220 they still didnt come on so I turned it off. For whatever reason the fans don't come on if I turn the a/c on like they are suppose to....But my manual fan switch installed inside the cabin still works.

Should I go ahead and replace the engine temp sensor in the wp? Would running in closed loop account for 5 mph trap power loss?

Note. the reason why the fans may not come in when the A/C is on may be due to the fact that I have no freeion in the system since it all leaked out....and the compressor never comes on.

I am about to pickup a ELM 327 scanner so I guess we will check it out. If the temp sensor is broke will it be ready very low compared to the dash temp sensor?

 

anyone?

 

The fans will not come on if the a/c system is inoperative. Use the scanner or meter to check the temp the sensor sees as people have been suggesting.

 

The temp sensor could very well cause your problems, but all you need to do is check the resistance with a meter (2 minute job) to confirm. If the temp sensor were that bad would probably cause a flooding/hard start condition to boot. If is checks out good there are several things that could would tie in better with your head gasket repair. For example: a leaking header gasket (where the flange mates to the head) will throw off you o2 readings or you could have a bad o2. The rockers could be a little to tight, id think that would cause a hard start/backfiring condtion as well though. Vacume line to the fuel pressure regulator damaged/broken... Should cause more problems in the low rpm's. Wow i guess i should think of something that matches the symptoms better. Does the car throw any codes? I think your on the right right track with the temp sensor, a 2.99 harbor freight meter would save you a lot of worry/trouble though. Good luck

 

Well I ordered up a scanner yesterday (got one for about $28) I plan on using the datamaster software. So I hope with the scanner I will be able to test if the temp sensor is working right as well as if the 02's are correctly working.

The only thing I still am not sure about is if any of those would effect WOT, I know the O2's wouldnt but what about the temp sensor?

Sometimes it is hard starting...where it takes 2-3 seconds of cranking instead of firing right up not always though.

I'm sure the scanner will tell a lot, I am going to need some help as to what looks normal for the 02's and wahtnot.

 

Yes your temp sensor will absolutely affect WOT operation if it malfunctions enough. If it doesnt report a high enough temp it will not go into closed loop and read the o2's ever you will be running rich stuck in cold start mode. In the stock programming the wot fueling will be as rich as 8:1 a/f iirc.

A good check for your coolant temp is if the engine has cooled over night plug the scanner in and check the engine coolant temp reported by the pcm against the iat. They should be very close if everything is at ambient temps.

You can also watch the coolant temp reported against what your gauge in the dash says for a sanity check as it warms up.

Just a fyi if you get too much teflon tape on the threads before you put it in it can cause malfunctions with electronic sending units like the temp sensor.

 

The thing is, I always thought at WOT it read from tables and never took sensor data..which is why w/ pcm tune they typically lean out the WOT table?

Otherwise, basically what your saying is: If I got in my car, turned it on and did a WOT run it would be a lot slower than if I let it warm up than do a WOT run?

 

No thats not what i'm saying, it has two different tables it uses. If its not reaching closed loop it commands a/f a different way than when its in closed loop. For open loop it just looks it up in a table thats map vs temp in c. In closed loop it looks at two different pe tables one is enrichment vs coolant and the other is vs rpm to decide how much fuel to add. Try running your car at -40c (shorted temp sensor) wot and i garentee you it feeds you an air fuel ratio of about 8:1.

Although some claim cars respond to pe tables in open loop. I have not seen it and my car doesnt repsond to changes.

 

I've noticed the car is hard starting sometimes when its cold, and occasionaly when hot. Would a cold hard start be caused by the coolant temp sensor reading ultra low at cold start?

I didnt realize I ordered my datalogger from china so it'll be two weeks before it comes...I may just run to AZ and buy a new temp sensor and see what happens then wait so damn long.