Is it my injectors?

[88grandmarquis]

Ok, my 88 gmq has a slight stutter when i accelerate. It only happens when it is in gear, not in park or nuetral. Can anyone help me figure this out?

[91waggin]

Check for codes.

Test throttle position sensor for dead spots. Put a voltmeter (analog actually works better in this case, since you can see the smoothness of the needle movement) on the two not-black wires.
Have someone slowly and smoothly apply full throttle with the key in the on position, but without the engine running.
You should see a smooth increase from nearly 0 to nearly 5 volts as you open the throttle. If there are dead spots, replace the TPS.

[gadget73]

standard tuneup questions first: how old are the plugs, wires, cap, and rotor? What condition are they in? How old are the fuel and air filters?

If thats good, and a code check does nothing for you, try unhooking the EGR valve. Its the green hose on the can thing next to the throttle. If that makes the hesitation go away, probably the egr regulator is sticky. I was able to fix mine by squirting some wd40 in the vent tube on the regulator. If unhooking the egr does absolutely nothing, your problem is elsewhere.

[88grandmarquis]

I belive that everything is original on the car. I just bought it 2 days ago and drove it for the first time earlier today.

[gadget73]

do a tuneup and see what changes. Can't diagnose much without known good basic stuff.

[88grandmarquis]

Alright. Whats a rough estimate on a tuneup? Cause I'm a little tight on money at the moment. And I really appreciate the advice.

[Lincolnmania]

spark plugs 2 bucks ea
wireset 25-50 bucks
cap and rotor 15-25 bucks
fuel filter 10 bucks
air filter 8 bucks
pcv valve 3 bucks
pcv gromnet 4 bucks
pcv screen 6 bucks

[88grandmarquis]

ok cool, I should be able to do that this week. Thanks guys.

[gadget73]

just some suggestions on parts, Motorcraft or Autolite (made in Mexico only) plugs, just basic copper core ones
distributor cap with brass terminals
not the cheapest wire set you can find. Duralast Gold, Napa Premium, whatever. You want the better wires, cheapo ones just suck and they don't last.

[88grandmarquis]

could it be a possible vacuum leak? cause if i am sitting next to a building at idle i can hear a hissing noise.

[1990LTD]

is it much louder when you're standing outside the open engine bay? the suspected vac leak, that is.

grab a length of spare vac hose and hold one end to your ear and try to trace the noise around the engine bay with the open end of the hose. it should make itself evident.


all kinds of noises from your car will bounce off of buildings because the sound waves have lots of room to propagate and you're getting sounds from the entire length of the car. the highest noises need the least amount of room to propagate - think of whispering - so that's why holding the open end of the hose around the engine bay will pick up the hiss hiss hiss easiest.

[88grandmarquis]

ok i'll try this and get back to you. lol cant right now cause its really storming out right now lol

[rick99601]

ill bet it needs a new timing set

[HATNINJA]

to find vacume leaks i spray starting fluid around the suspect areas the engine will rev up when you hit it. but just because you dont find it this way it dosnt mean you dont have a vac leak.

[gadget73]

starting fluid is awful volatile. Get that around a bad plug wire and it might blow up in your face. WD40 is somewhat safer and will produce the same effect.