OK so my 87 t2 is driving me nuts! It started out with when the engine was cold, it would buck and bog down a bit. This would usually only last a bout 1/4 mile or so. Then about 3 months ago, it started to buck and bog down after it had been sitting for about 10 mins or more. The engine was still hot. Coolent at 175 or above. It was pretting much the same as above otherwise.

Now it bucks and bogs from starting (hot or cold) and just stays like that. UNLESS i am accelerating. then it drives more or less normal.

Of course today after I did a few tests I took it for a test drive. Drove fine, just like normal. Stopped it, walked around a small park, restarted and drove home. Worked fine. Took shower, drove it to get some dinner and then down to the waterfront to eat. Worked fine. Started it after dinner and Wham! right back to running like crap. Had to accelerat and coast all the way home.

I've checked my fuel pump voltage 8.75volts my pump resistor, which tested fine. Put in my spare, but new, fuel filter just incase.

It idles fine 775ish with my AFR at about 13-12.5 Vacluum is at 15mmhg
Intake temps are quite reasonable at 115 for first and 110 at the tb.
AFM appears to be reding fine. .6cmf at idle 5 or so while "accelerating"
injectors appear to be be working with anout 2.5ms @ idle and 5ms while driving.
When the car bogs and bucks the AFR goes LEAN (20) and the vaccume plummets to 3mmhg
Atmo sensor reads right.
tps reads right.

It seemed to work today when it was warmer out (80) and then after dusk when it cooled down is when it started to drive bad. I have noticed this befor as well. Drove it 120 miles a week and half ago. Nice 85* day. no proplems at all. Yested day it was like 65 and it was undrivable.
So is this enough info?

Let me know what else I should check.
I'm going to reset my rtek right now just for gets and shiggles. (won't help)

 

Have you checked the water thermo sensor? I think thats what its called. Located right behind the water pump, with a green clip similar to a injector clip.

 

not yet. I cant rember but is that the one that reads the water temp for the gauge. My ECU is reading correct.

 

I checked the FSM and the thermosensor you mention does indeed work the gauge. My rtek shows the temps as beening normal. I suppose I can pull it and test it but i suspect it works correctly.

 

Try driving the car w/the TPS disconnected and see if that changes anything.

 

The temp sensor for the gauge is on the rear iron, the one on the water pump is for the ECU, perhaps the rtek is reading it fine at idle, but the sensor clip may have busted? Comes loose a bit while driving?

Have you removed the secondary butterflies of the TB?

 

If the injectors are using the same duty cycle when the AFR goes lean, it almost sounds like you have a big intermittent vacuum leak.

Not that I have any idea where it would be... GL.

 

Bringing this back as I havn't had much of a chance to change anything. I checked the basic fuel stuff first. Changed filter, added pressure gauge inline. The fuel pressure is a bit high, but nothing that should cause problems with running lean. I pulled the UIM to double check the vacuum hoses (I hate the tb coolant hose!) and they seemed fine. I did a quick once over of the wires, crappy, but shouldn'be a problem.

Going to try disconecting the TPS tommorow.
My other thought, is spark.
I have a jacobs FC 1000 mounted to my leading plugs. I'm thinking that if this thing had been slowly going bad, that might be causing probs. Any Ideas? What about the trailings If the coil pack doesn't have a good ground, or is going bad could that cause the problems?

Oh and the throttlebody is stock.

 

Well i managed to pull the temp sensor off today. ECU reads 178 as default. Took me a while to figure out the temp gauge sensor. I just assumed they where the same since my rtek shows me the temp. But no, they had to have one just for the gauge. So is that all the gauge unit does, send info to the gauge? I don't want to pull it if it doesn't contribute to the engine management.

 

The IAT at the throttle body is for engine management. The sensor for the temp gauge is just for the temp gauge.

 

Have you checked the fuel sock, the strainer at the bottom of your fuel pump?
I had all kinds of problems like yours until someone here told me to just change it out, it was like magic. The old one looked OK but it was plugged and a yellow/brown colour, new one are white and cheap $12.00. Change that screen and report back!
Mike

 

Hey satch (I still havent disconected the tps) I don't think I refered to the AIT anywhere. The bit that had me confused was the two water temp sensors. Some one said check the rear one and in the process I discoverd that it only works the temp gauge. The confusion came from reading my exact temps from my rtek. Its "gauge" is the actuall temp of the front water sensor. My AIC seems to be right on as well.

Havent checked the old sock-a-roo, but it isnt' too old. I put a walbro in about 20k miles ago and it got a new one then.
On that note, if the sock was plugged Would I still get 40 PSI at Idle on my fuel pressure?

I just want to drive a damn Rex again!!!!!!

 

Well it looks like it was the o2 sensor. I had it using the NB output from my wide band and after logging a few attemps at driving i noticed it was only reading from .5-1 volts. I swapind it back to my stock one and the car is actually drivable! woohoo!

The cold stuff looks like a combination of my temp switch working only when it feels like it. And my thermo wax cools down way to fast. After only about 15 mins it forces the TPS back to 30% at idle. I'm not sure if its the "pelet" or maybe the coolent just not staying up there.

God I forgot how much fun it is to take the "cloverleaf" offramp from the freeway doing 50!