my 89 i-roc 5.0 auto rns great when i first start it.il drive it till its good and warmed up run in some where real fast then it mite start mite not without either.when it diuse start it runs real rough an i can feel a bad hesitation/loss of power.iv checked everything i can think of new plugs wiers timing set new k&n air filters new fuil filter,tps,and distributor if anyone has any good ideas let me know thanks

 

need more info ... is this a carbed engine? if not ... sounds like a sensor problem. is the check engine light on? Sick

 

Sorry its a TPI car.has biger injectors and air intake tubes.and i had to resently put a new distribitor in it

 

As Sick said, is the check engine lite coming on?

 

it comes on for a min or so and gose back off but only after iv gone some wher ,shut it off and turned it back on still at normal temp

 

try using a scan tool and seeing if you get a code, either that, or it sounds like a solenoid problem, it could also be a crank sensor, i ran into a taurus that did the same thing but it was the crank sensor in the end.

 

Runs good cold, then performs poorly warm. The ECM takes over control once the car goes into closed loop ( warmed up and ready for ECM control). I am assuming the problem starts when the car does go into closed loop control.

You need to have the proper scanner to look at the data and then look for anything odd. Like a coolant temp sensor well off. A MAF reading that makes no sense, a Baro reading off, look at the trim numbers and see if they are going way lean or way rich.

First step to do, and get the codes listed in here, it may speed up the process...

 

showing code 13 &44 o2 sensor & o2 sensor lean could this cause my problems changing the sensor tomarrow.also i did just buy this car in november today i pulled the e.c.m. out to look in it and it has a hypertec chip.

 

Not neccessarly. If the car has a lean condition the o2 may flag a code because it's stuck lean. Take into account the age of the car, if the 02 has been serviced in the past (they do have a life expectancy) it could warrant changing.

Any testing? volt meter or waveform on the o2 sensor and try to force it rich (add propane) and see if the o2 reacts to it. I hate swapping sensors without testing but if you need to do that, test by replacement, then after putting in a o2, clear the codes by disconnecting the battery and take it for a test run. See if anything changes. If it still acts up the same I would guess you have a lean condition causing the lack of power.

Look to fuel pressure and volume then, after that, for fun, try unplugging the MAF and take it for a run and see if it runs better warmed up. Fact is, try unplugging sensors one at a time and see if it improves. You may find a shorted sensor causing the problem. Coolant temp sensor, MAF, Baro, 02, all that stuff could short and cause a poor signal. I'm doubting a fuel delivery problem since it runs good cold. This screams of a sensor gone bad or a ECM fubared(along with a bad PROM). These aren't "test methods" I am giving, but try them if you don't have equipment.

The tap test also works if your not testing with scanners and such. Give a slight tap to the ECM and see if the car reacts, give a light tap to the MAF and see if the car reacts. Just don't hit it hard please. Tap relays along the firewall.

These are not really good test methods but if you lack a scanner and DVOM to test with it may be your only course if you want to do it yourself.

 

I changed my o2 sensor and cleaned my MAF sensor. I let it sit over night last Tuesday to clear code's ran better than ever until today when it started the same stuff. I unhooked the MAF sensor no changetap relay's check all sensor's ????????? I have noticed that sometimes I'll shut it off and i can here the fuel pump stay on anywhere from 5 or 6 seconds to all most 20 or so. Ithas good fuel pressure is that normal? also how hard is it to just go carburated I'm lost with this T.P.I.