i have a 87 coupe 5.0 here is my problem when i drive it, it will sputter through the gears like there is no power or gas to it i have replaced these parts so far timing chain, tps sensor, idle air sensor, fuel regulator, fuel filter, pick up coil in the distributor if you have any answers that might help i would be thankful

 

You need to be more specific please- when does it happen? cold, hot? low speed, high speed? every day, once a week?

It is engine RPM or vehicle speed dependent?

 

it happens when it is cold and hot, it has been happening every day now for about 3 months, and it happens when you exclerate and when you are criusing and it back fires some times also when driving

 

I don't mean to be annoying with all these questions, but I am just trying to narrow the problem down.

The sputtering and backfiring seems like a fuel mixture problem or ignition timing issue, but there are some internal mechanical things that could cause this as well.

Here we go:

1) If it happens when you are full throttle and mid throttle than is it safe to say that it's NOT RPM dependent?

2) Are you unable to touch the throttle without it sputtering or does it seem to not idle properly at all?

3) What color is the coolant? Is it very dark?

4) What color is the engine oil? Does it look like a milkshake?

5) When was the last time you replaced the 02 sensors?

6) Having replaced the fuel filter, regulator and pump- did you also clean or inspect the fuel injectors?

7) What is your initial ignition timing at? (I'm assuming that you have an electronic dist. that you can still turn)

 

2. it ideals fine and is very responsive when i hit the gas.
3. the coolant is new but when i drainded it it was a rust color and that was due to using water that had a lot of iron in it i belive.
4. the oil is fine always changed at 3,000 miles
5. i have not replaced the o2 sensor
6. i did not check the injectors
7. it is at 10 degrees

 

I believe you have one upstream O2 sensor per bank/side. Also, 1988 was the last year for the speed density system- which means that your O2 sensors and MAP (manifold absolute pressure) sensor are your primary inputs to the eec for fuel adjustments (after it enters closed loop operation). The CTS (coolant temp. sensor) lets the computer know that it can enter closed loop operation. They reason I bring this up- it that this may be a cause for an overly rich condition. This is also why I asked if engine temperature affected anything.

So, things to check- CTS, O2s, and MAP. You can back probe the sensors to verify that the correct voltage corresponds to the right value (CTS- voltage and temp, MAP- voltage and manifold pressure {positive or negative}, 02 0-.5V {.5V is fully rich, 0V is fully lean}). A properly working O2 sensor will switch up and down while the engine is running, so it is acceptable to be around .250V or 250mV.

Please note: that I have learned that 1988 may be a crossover year for the introduction of the MAF system. If you have a MAF sensor- than you can disregard the above, and I will try to help you later with that setup.