I’ve been battling this problem since I’ve bought the car(87 T2). This is what it does. It will idle high(like 1 grand and up depending on its mood) When I go to accelerate the shift light comes on a 4 grand, and I have little power. It smells like its running rich. Some times if I stop somewhere(like to grab something to eat or visit somebody) When I get back into the car it idles 500-750 and runs like a bat out of hell. When this accurse It will run good for awhile unless I go on the highway for a while. These are the thing that I’ve done.

1 Upgraded ground
2 Spark plugs and wires
3 Out of sheer frustration Removed emissions and vac spider
4 Fuel filter
After doing the above my average idle has gone down. When its running like crap its about 700-1500, and when it runs good it bogs down to 300-500 and likes to stall and flood itself if I doent push the pedal at red lights.

Some more thing ive done.
5 Made a new wire harness (replaced injector plugs)
6 TID MOD (because after removing air pump I noticed a crack in it. I was so exited I was sure that was the problem. But come to find out it didnt change a thing.(I was pissed)
7 Tested all sensors except the water thermo and the O2 sensor.( how do you test an o2 sensor)
8 checked TPS along with the sensors
9 put the Pill in the vac line that goes to the boost sensor.

Thanks for reading all that, Ive searched the forum and found no simaler problems. What could cause it to run good after sitting for 30minute to a couple of hours.

 

Why don't you just replace the o2 sensor and water thermo sensor.One of those can cause your symptoms.

 

To check a O2 sensor you can either back probe the o2 wire and you shoudl be getting a changing signal. The signal should be bounce around 3 to 8. I am don't know about the FC yet but you should really check the engine coolent temp sensor to see if is in spec and if you have a air charge temp sensor you should also check that. My NA FC have a map sensor and again i am not sure about the T2, checking the vacume hose to the map sensor and checking the voltage on the Map sensor might also help.

 

The map sensor in a rotary is called a boost/pressure sensor.

 

Thank! what is the location of this sensor? After intercooler?? Does T2 also have a air charge temp sensor??

 

1 The boost/presure sensor is infron of the passanger strut tower. It sould have a vac line to it.

2 Yes its in the intake elbo before it goes into the motor. you will have to take the intercooler off to see it.


I have already checked that sensor and its good. How much is the o2 and the water thermo sensor cost. could my problem be the ecu. Can an ECU act moody like this?

 

Well i dont know about you but I cant just spend 200+ dollars on some sensor that i dont know are the problem. Im a poor boy here.

How do you test the o2 sensor. The disciption above is vag? is that volt you are talking about?

 

You can check the parts section of this forum for the water thermo sensor.The o2 sensor is relatively inexpensive at a parts store.The o2 sensor is supposed to be changed out every 60k miles as routine maintainance.

 

You can check the parts section of this forum for the water thermo sensor.The o2 sensor is relatively inexpensive at a parts store.The o2 sensor is supposed to be changed out every 60k miles as routine maintainance.

 

Sorry about the mess up instruction on testing the O2 sensor. I was a tired at the time plus i am not great at English. Alright i will try to give your the instruction again i hope i can make it clear this time. On most car especialy with a older car the 02 sensor produce a voltage when o2 pass through it. And since the computer will try to tune the Fuel/air ratio to 14.7 the computer will make the make the mixture rich- lean -rich lean over and over again. Back to the o2 sensor now! IF the computer is making the mixture rich lean rich lean all the time the O2 reading will change from rich to lean and back. If you have a voltage meter and you back probe the O2 sensor wire you will see the voltage change around .8 to .3. In most case the richer the car is the higher the reading will be. Again that with most cars, but you could go to one of the Online Manuel and check out the trouble shoot.
As for the engine coolant temp sensor you can test to see if the sensor was bad with out even getting a new one.
There is two ways.
First back probe the sensor after the connection and see if you are getting a reading. Remember to check it in Ohms!!! The lower the # the hotter the coolant is. Again i don't have the range with me but you can check the resistant before warm up and after warm up to see if there are any changes too see if they are within specs.
Second way: This is a easy and cheap way to check the operation of the sensor. I tried this on a project supra of mine and nothing bad happen so here it is. Since the computer is trying to see how much resistant is within the sensor. You can trick the computer to think that the car is cold by bridging the two end of the connector. This will give the computer a signal that the car is hot. Or if you want to play it safe just unplug the sensor all together it should run very very rich.
Well buddy i hope this helps that about as good as i can do on the direction.

 

I checked with MAZDA and they said that the o2 sensor was around $250. Where can I get one cheaper. I would pefer new.

 

twistedriver when I test the o2 senser, do i test it when the cars running. THANX FOR ALL THE HELP GUYS.

 

Why don't you buy a o2 senor at your local autostore. with harness is should be no more than 40 dollars.

 

It is not the o2 sensor period. Sorry man. You can unplug that thing and your car will be fine. Just get bad highway mileage.

How does it perform when you floor it from a standing start? It will hit a wall at 4000rpm?

James

 

Ya my shift light comes on and theres no power after that. Ive inspected the injectors and wired new plugs, It all looks good. Does the commen hesitation problem that ive read on many post cause it to run rich.

 

Update I replaced the o2 senser and the water thermo senser. Still run like crap.

 

listen up, this is close to what was happening to me this week. First off I was hitting a wall at like 4000 rpm. It was a bad injector. One of the secondaries was bad, I threw power and ground at the injectors and noticed one was clicking very faintly in comparison with the other. I took it out and the car felt much better but still had hesitation. I replaced a lot of stuff with parts from my donor to try to figure out the problem and it came down to this. First off go to your ECU, find the four points on the harness that are grounds (2c,2r,3a,3g) Splice in a length of wire to these four locations and put a ring terminal on the end of them and bolt them to one of the ecu bolts. An ecu grounding problem could be your problem. Doingthis on my car on wednesday made a huge difference in my hesitation but did not get rid of it. The thing that got rid of it was changing the boost sensor. Just give these 2 things a shot and I bet one will fix your car. 1---Ground the ECU 2---Replace boost/pressure sensor.

 

The ECU grounding idea was Hailers's, and if anybody knows fc's, it's him.

 

Hey try this!! I know you tryed everything already and i was just think why don't you change the injector 0-rings?? I mean my teacher has incounter a similar problem a while ago. When an injector 0-ring was harden making it hard to start at hot temp. ANd if the 0-ring crap out you could also have a vacume leak. Also did you check for vacume leaks at all?? And yeah check the computer grounds while you are at it. I hope this helps. Hey buddy i am sorry to hear that you spend so much money on the sensor!! The same thing happen to me when i had a 87 supra. I never fixed it but my plug for the coolent temp was mess up so that might have been the problem. But i never figura out what happen with the supra. Well good luck buddy hit me up on what happen alright??

 

The new sensors where not to much from autozone. About $20 a peice. Funny thing. I just replaced my o-rings right befor i read this. I found 2 injectors that had cracks on the bottom nipple of them. I think this is my prob.

 

Did you break the injector air bleeds. The brown plastic things inside of the injector socket?

http://www.mazdatrix.com/c-6.htm

And do you have have the injector grommets there?

James

 

If I remember corectly when I bought my O2 sensor at autozone it was $50.

 

Tried doing an error code scan on the ECU?
Shift light triggering at 4kRPM sounds like a pretty bad problem...


-Ted

 

The Bosch 02 (Part #11027) sensor is $39.99 @Autozone. If you live near O'Reilly Auto, the same sensor is only $23.99... they don't have online ordering

 

So if the shift light comes on at 4 grand is bad??? Or am i reading it wrong RETed. I am not wrong price of a O2 sensor goes up if it has the connecter and everything. How do you retrive the codes for S4 7s any ways??