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Question

new engine running rough


Sent to Car Experts August 12, 2006 10:38 p.m.

i have a '92 isuzu trooper. 3.2 SOHC 6cyl. (6VD1) engine.   i had a reman Jasper engine installed 1 month ago ($6000). it was running great and then the other night i got in to drive it and it was running really rough and had very little power. i looked under it and saw the catalytic converter glowing red hot. i replaced the cat and muffler thinking it was plugged up. it is now nice and quiet but still runs the same. it has 280K miles, a new O2 sensor, new plug wires, plugs and obviously a fresh motor. any ideas??

Optional Information:
1992 Isuzu trooper 6VD1

Already Tried:
new catalytic converter and muffler
Customer (name blocked for privacy)
Status: Closed   Value: $9   
Answer
August 12, 2006 11:08 p.m. (29 minutes and 54 seconds later)
REPLIED Check Mark

Greetings! I think u have a lazy or bad oxygen sensor. The heated oxygen sensor is very important to control not only the cars emissions but it also helps the vehicals performance! If it is not working properly it can result in a number of problems like rough running stalling hesitating bucking and jerking. But more common than that if it is lazy, the cars gas miledge will drop considerably, and sometimes not even set a check engine light on the dash!
The fuel control Heated Oxygen Sensor (HO2S 1) is mounted in the exhaust manifold where it can monitor the oxygen content of the exhaust gas stream. The oxygen present in the exhaust gas reacts with the sensor to produce a voltage output. This voltage should constantly fluctuate from approximately 100 mV (high oxygen content - lean mixture) to 900 mV (low oxygen content - rich mixture). The heated oxygen sensor voltage can be monitored with a scan tool. By monitoring the voltage output of the oxygen sensor, the PCM calculates what fuel mixture command to give to the injectors (lean mixture-low HO2S voltage = rich command, rich mixture-high HO2S voltage = lean command
PictureAMEDEE  -- ASE MASTER TECH -- 98% Positive Feedback on 1036 Car Accepts
ADVANCED LEVEL SPECIALIST
Answer
August 12, 2006 11:31 p.m. (23 minutes and 18 seconds later)
ACCEPTED Check Mark

I know u said the o2 sensor is new, but if you have a aftermarket one than it will not work like it should. Or it may be bad! I get bad new parts all the time! If u r sure the o2 sensor is working just fine, than my next rec is recheck the tune up parts. These could definately cause the convertor to run hot if they are bad. Try to locate what cylinder it is on and pull out that plug. It just may be cracked!
PictureAMEDEE  -- ASE MASTER TECH -- 98% Positive Feedback on 1036 Car Accepts
ADVANCED LEVEL SPECIALIST
Reply to amedee
Sent August 12, 2006 11:45 p.m. (13 minutes and 22 seconds later)

yeah, but the O2 sensor i have is like a month old. i just looked at it today when i changed the exaust and it is new...it might still be bad though? i was paranoid that it was my ECM or the DIS...which meant lots more $$$
Customer (name blocked for privacy)
Answer
August 13, 2006 12:08 p.m. (12 hours and 22 minutes later)

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PictureAMEDEE  -- ASE MASTER TECH -- 98% Positive Feedback on 1036 Car Accepts
ADVANCED LEVEL SPECIALIST

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