PCA Forums

well my car still has probs....

when I accelerate, it bucks violently



So i took it in to have it checked out and i was told of 3 possibilities

-bad wires from the sparks to the distributor cap
-bad EGR valve
-bad air compressor (or something like that)


So right now I replaced the wires from the distributor cap to the spark plugs (and even the one from the cap to the igition coil). It appears as those were still the origional wires that came with the car (1988 grand marquis)

That seemed to help with the lower speeds, but when it goes around 40mph and higher, the studdering still occurs.

So now I am gonna try to replace the EGR valves cause it appears to be withing easy reach. It is just after the air intake and before the upper manifold.

But I got some questions before I do anything, if anyone knows.

Is there anything special i have to do when I replace this? or can I just disconnect it, remove it, put new one in, reattach everything?


I will be happy once my car works 100% again

The EGR (Exhaust Gas Recirculation) valve is part of the emission control system that does what it sounds like - when it operates it actually feeds some exhaust back into the cylinders to lower combustion temperatures and prevent formation of nitrogen oxides that didn't get combusted the first time. Since engine management computers expect the EGR to be working, fuel, air and spark decisions are made as if the valve opens when it is supposed to.

EGR valves are either vacuum operated or electronic. Either way, they are supposed to open when commanded by the computer. If you know how, you can kick the computer into a field service mode and make it give the command to open the EGR and then check to see if it is working.

Look here for more on EGR: http://www.misterfixit.com/egrvalve.htm

However, I don't know crap about Fords. If you have a vacuum operated EGR, you could apply vacuum with a handheld vacuum pump and see if it opens. Even if you don't, you should check to see if a vacuum hose not attached to the EGR.

Did they say Air Pump? 88 is kind of late to have an Air Pump (also part of emissions). An air pump is likely to be expensive, I think. I don't know how to test them either.


An EGR valve is usually very easy to swap out. You can do it without any fuss if you don't end up with too many parts left over. However, they run anywhere from $40 buck to a couple of hundred and I hate to see you just replace parts without a better idea of what is happening. Unfortunately, cars are so complicated now that your symptoms could be caused by any number of things. I have a friend who used to be an engineer for GM. Needless to say, he knows cars. He spent about 3 months trying to figure out a problem like yours and it turned out to be a loose ground wire!!!

Do you have a "check engine" light? Does it, or has it, come on? Does the bucking happen more at some times than others? Is it worse or better when the car is dead cold or when it warms up? (When the car is dead cold, the computer is in "open loop" and just runs the engine on a preset program. Once the car warms up and all the sensors are operative, including the oxygen sensor, the computer reacts to all of them and does more sophisiticated crap.)

Bad plug wires can be checked several ways. The easiest is to drive the car to a dark, dark, place on a moonless night. Pop the hood and check for a light show where the plug wires are. If the problem is worse when it is wet or damp, that usually means bad plug wires too. If you have an ohm meter, check the resistance of the wires. If it is greater than 10K ohms per foot (check this on the web, it might be lower), then you have bad plug wires.

Feel free to email me with any questions. I will be happy to help any way I can.

Air pump? that wouldent have a thing to do wiht it bucking.... all the pump does is inject fresh air into the exhuast so that the unburned crap can have air to burn with in the cat. hell.. i took mine off my car when i chaged the fule pump and havent put it back on since... im probbly gonna fail emmissions... but i work for them... i know a few tricks

thanks for the info Lmandrake

from what the mechanic said when I had my car looked at, that if it is the EGR, it would cost about 80 plus labor through them



and pugsley: i cant remember the name, it was air something something. Of course i could be wrong.
I know i got it written down somewhere around here