Ok I'm still having a problem even after taking it into the shop 4 times. The car backfires from the exhaust. It is worse on a cold start. Sometimes when I idle the car will backfire loud once through the exhaust. When i took it into the shop they scanned for codes found a MAF problem and they replaced the MAF sensor. That only fixed the hesitation i had. They also noticed that my o2 sensor was barely hanging on and made it nice and tight. I took it back in and they drove it, scanned for codes and could not come up with anything. They told me to get some dry gas and some fuel injector cleaner. So i got dry gas that had fuel injector cleaner in it. Poured the whole bottle in and ran through an entire tank of gas. That didn't work so I took it back and they told me I need my computer not to get readings from the o2 sensor so I went and did that today and a mile down the road two loud backfires. I'm out of ideas replaced the coil few weeks ago, plugs and wires are about a year old. Car starts up fine and never stalls. please help!

 

WTF does that mean You disconnected one or both of the O2's. So now you are running in open loop. If so that could be helpful in determining the problem or the next experiment to attempt.

I had to go to your profile to see that it was a 94. Not cool. You were asked before to add a signature with basic information.

You have said in previous conversations:
That you fixed the problem?
That you had a torn intake boot. (But never said whether you fixed it or not).
That you continued to have cracked spark plugs but never said if you replaced all of them.
That you noticed the tach goes crazy when you experience engine problems and backfires?
So what about these things?

Backfiring can be caused by several things:
Spark that is occurring intermittently or at the wrong time.
A lean running cylinder.
A rich running cylinder.
Valves that are not closing correctly or at the right time.

So the first question is when was the last time a complete and thorough tune up was done?

Since the occurance of the problem, were the plugs removed and checked to see if any show the cylinders were not running correctly?

After the plugs are checked, that will dictate what may be checked next.

 

I replaced the torn intake boot and replaced all of the spark plugs the RPM guage still jumps around. Number 5 or 3 cylinder can't remember I want to say #5 when i pulled the plug it was the only plug that was black. I also forgot that when i got my car scanned for codes they told me my Intake manifold pressure was 10 and should be 18 I'm assuming that 18 is the correct number. cap and rotor was replaced like 30k miles ago along with the water pump. Plugs and wires are less than a year old. I replaced the coil like 2 weeks ago. And I know i forget to get my signature I keep thinking I'm on a different forum

 

also the whole o2 thing was to make the o2's not to make the car run rich because my mechanic though that the readings from the o2 sensors were causing my computer to make the car run rich

 

The MAP pressure depends on what the operating conditions are, and what units of measurement are being used. Some scanners read in inches of mercury ("Hg) and others read in kilopascals (kPa). At idle, with a stock cam, a MAP reading of 10"Hg (35kPa) would be normal. At WOT, MAP should approach barometric pressure (also read with a scanner). At sea level, MAP at WOT should be closer to 29"Hg or 90-100kPa.

This might help you with the scanner data:

http://members.aol.com/InjuneerZZ/ScanMast.htm

 

Thanks Injuneer!

 

The o2 sensors are original. You think it's just time for them to be replaced?

 

I think its what the guy said in the second post about your valves, you should have them checked and adjusted. maybe when the exhaust valve is supposed to be closed its slightly open causing the exhaust to back fire. Makes sense to me..but im new to this all too.

 

might be worth checking your ignition module...

 

bump I'll check the ICM the valves ill put aside for a while as that would be a bigger job to do