95 Lumina Hesitation trouble- thought I had it fixed

[Shinobitoshi]

I apologize if this is a duplicate post. I have searched this forum and the Internet for weeks trying to get an answer. I have a 1995 lumina 3.1. It seems to idle fine, but when I am driving it sort of hesitates when I start from a stop and when the car shifts gears. I decided it was time for a plug/wire change, which I did. For about two weeks it ran great with no hesitation but for the last couple of days it has been back and bad as ever if not worse. I don't know what else to try. I tried braiding the plug wires because someone somewhere said would help. I did notice that the old plugs all had a lot of greyish buildup on them when I removed them. That's probably a sign of a different problem. Also, I replaced the plugs with the kind of plug that had two prongs on it. I don't know if that was a good idea or not seeing how they have a very small metal piece in the middle and could probably get fouled up easily.

I edited this post to add that I also noticed that one of the posts on the coil pack(?) on the far left has a rusty connection. Could his be something I need to replace also? I cleaned it well and took most of the rustiness off, but I didn't do that unilateral it started acting up again. So it was working fine even with the rust right after the plug and wire change.

Anyway, I'm rambling now. Any help would be greatly appreciated and if anyone needs more info just let me know and I'll
do my best to provide it. I'm not a mechanic though so I don't know how technical i can get.

thanks in advance.

[maxwedge]

Welcome to AF, hesitation means many things to many people, is this a misfire/engine roughness or a " flat" spot? From here we cannot determine what is acually happening.

[Shinobitoshi]

This is a misfire I beleive. It's not something that happens every time. It's almost like it gets no gas for a second and then catches up. Usually if i push the gas it takes a second for the car to get power back.

[maxwedge]

Like to help but this is too vague for any meaningful advice, if the plugs and wires are new and properly secured, check fuel pressure.

[jd-autotech]

take a 3/8 extention and drop it on your fuel injecters one at a time but dont hit the to hard .this will knock out the dirt in the end of the injector

[Shinobitoshi]

I had the fuel pressure checked and they said it was normal. I had a replacement fuel filter installed just in case. I also had my injectors cleaned. The car is still acting up. I want to scan the computer to see if it is throwing any codes, but I don't have a scanner. I understand that you can use a jumper wire to check codes on an obdi dlc connector, but my obdi connector doesn't have a b wire to jump the a wire to. Is the connector screwed up or am I not going to be a able to check it this easily. I tried checker auto parts, but they only scan obdii.

Would you think that a seafoam treatment in the pcv valve might help? I'm guessing it's misfire now that I took care of the fuel system. They guy who did it said my throttle body was filthy, but I can't see what else it could be now.

[Shinobitoshi]

i also just pulled all the plugs to see if they were fouled up since new plugs helped so much before. All of the plugs looks fine. They have a little crud on them, but it doesn't look like they are so fouled up that they aren't sparking.

I did want to ask also if a rusty connector on an ignition coil is a problem. I haven't been able to find much info on this, but i noticed when I changed my plugs and wires that one connector on the 5 2 coil pack is rusty. I guess I should check for spark, but I don't know if it would make a difference at idle since it only seems to have problems when the engine speed drops as I slow down or when the car shifts gears.

I suppose it could also be some sort of air flow problem. I replaced my air filter when I did the plugs and wires. Would it be best to check the 02 sensor, the MAF sensor, or the MAP sensor first?

[Shinobitoshi]

well I decided to replace the coil since the part wasn't a horrible price, but that didn't help the problem.

I was also wondering if this could be an EGR valve problem. I noticed that the EGR valve is located just past the throttle body assembly and the guy who cleaned out my injectors and fuel system said the throttle body was bad. Could crap have gotten into the EGR valve during the cleaning or, if the throttle body was fouled up, could that be a sign that the EGR valve is clogged? How would I test to see if the EGR valve is working properly. I found a ton of videos on youtube, but they were all on a different type of valve.

[Scrapper]

it could be the module under under your coil pack or your maf sensor but really sounds like one of the coil's in coil pack.

[Shinobitoshi]

Like I said I replaced the coil with the rusty terminal. But it didn't help.

[manicmechanix]

Did the guy clean your throttle body? He said it was dirty but did he clean it? It really hard to tell what kind of hesitation you are having like Maxwedge said. It sort of sounds like you might have an ignition misfiirng situation when you are under high vacuum conditions like between shift, but I'm not sure. I think you should use original AC type plugs gapped around .045. Check the coil primary (and secondary if you happen to have the coils off) and ignition wires resistance. Look for vacuum leaks. It'd really help if you could get a scanner on it, but you have that wonderful '95 OBD 1.5 that no one seems to have the scanner for. Just for sh1ts and giggles see what happens if you unplug the EGR connecter wire.

[Shinobitoshi]

He cleaned the throttle body. Do you mean I should drive
it with the egr disconnected? I unplugged it and let the car idle until it was
warm. Then I revved the throttle. I saw no difference
when I did that. I thought about switching back to regular plugs, but why .045? Spec is .060

[manicmechanix]

OK did you drive it with the EGR connector unhooked and no difference? The reason I suggest a .045 gap is I was thinking your spec was .045 and not .060, but also because sometimes .060 is too much and gives problems. If the spec calls for .060, use that or tighten it up to .055 or so. Is this hesitation you are getting kind of jerky feeling (most likely ignition) or is it more like the engine just flattening out (most likely fuel injection related)?

[Shinobitoshi]

I didn't drive it with the egr unhooked. I only let it idle and used the throttle to rev the engine. Why would regular plugs be better for this car than the others? Just wondering. It's hard to describe the hesitation. Almost always it kind of jerks a couple times and then feels like it has no power until it revs back up. Sometimes when coming to a stop it does the same, but without the jerking. The closest thing I could describe it to is like trying to start a standard from a stop in third gear.

[manicmechanix]

People have had problems using non original plugs. The o.e. plugs will give you o.e. performance. Revving the engine in neutral won't tell you much. You have to drive it under the same circumstances that caused it to act up. What you desribe sounds like it might be an ignition misfire.