I have a 98 3800sc and it seems to have a constant miss but I am unsure. While driving it, it shakes when I shift to a higher gear (like 5th at about 45-50 mph). If it is missing, I know it has to be fuel or fire so I started to pull off the wires 1 at a time from the coil pack and it didnt seem to make much difference at all if any. I got bit around the 3rd one and stopped there. I also pulled a plug to see what it looked like and realized I had put in the new plugs from my 2.8 to keep it sealed up and forgot to get plugs for this engine. The ones in there now are the AC Delco R42TS which at best were only used up till 96 but mostly mid to late 80s engines.

I am going to get a set of plugs but would these effect this engine this badly?

Which would be the best plugs to get? (stock 3800sc)

Any common problems with the 3800sc that the shacking at low rpms sound like?

I really have no gauges or meters to try to check the injectors or fuel pressure. It seems to be getting plenty of fuel and the rear of the car tried to swap lanes yesterday in 2nd gear so there is power.

Steve

If you just put plugs out of your 2.8 in the 3800, did you forget to gap them when putting them in too? Too much or too little could cause odd issues. Get the feeler gauge out and check them.

And yes, if the 3800 needs plugs with a different heat rating, having the wrong ones can cause odd issues as well.

What is "low RPMs" here? Does it only do it in 5th, or at idle and in other gears as well? If only 5th, maybe something wrong in the trans?

Thanks, It shakes in any gear at low rpm. Thats one reason I thought it might be a miss, at higher rpms, a miss is less noticable. I also just noticed that when I screw the plugs in, it only takes 1 turn before it stops. I was thinking it should be atleast 3 maybe.

Im sure the heat is different on the plugs for the 3800 and I never set the gap because I was intending to replace them and forgot. Just plugging the holes with these.

Steve

quote Originally posted by dobey: What is "low RPMs" here?

anything a SBC turns . . . (runs laughing and jumping in bunker for cover)

------------------

ARCHIES JUNK IS FASTER THAN SHAUNNA'S JUNK
12.3 is faster than a 13.2

quote Originally posted by JumpStart: Thanks, It shakes in any gear at low rpm. Thats one reason I thought it might be a miss, at higher rpms, a miss is less noticable. I also just noticed that when I screw the plugs in, it only takes 1 turn before it stops. I was thinking it should be atleast 3 maybe. Im sure the heat is different on the plugs for the 3800 and I never set the gap because I was intending to replace them and forgot. Just plugging the holes with these. Steve

Yeah that is way wrong.

quote Originally posted by phonedawgz: Yeah that is way wrong.

this aint helping me any. lol

EDIT
I took out a spark plug from a 2.8 and a 3800

The threads pitch are the same

The number of threads are WAY different

Putting a short thread 2.8 spark plug tightens in about 1 turn

Putting in the proper thread 3800 spark plug takes 6 turns before it seats.

You just have the wrong spark plugs in your 3800



The plug with the longer threads is for the 3800!!

--------
Before edit

quote Take the sparkplugs of the 3800 and compare them to the plugs of the 2.8. Are the threads the same? If the threads are messed up, you can use the PROPER spark plug tap to repair them, assuming you only went into the heads 1 to 2 turns. The beveled seat of the outside of the spark plug shell needs to be in contact with the corresponding seat in the head. They need to screw in that far. Spark plug taps can be obtained at parts or tool stores.

[This message has been edited by phonedawgz (edited 09-10-2011).]

You are Da Man...Thank you. I will pick up some new ones tomorrow. Any suggestions?
Also, what would I need to read OBD2 codes?

Steve

idk re spark plugs.

I use dyno-scan to read my ODBII codes. I bought it years ago and I don't know how it stacks up to the competition now. I am pleased with how it works however. I think they have a download simulation version available.

Dyno-scan can't program the PCM however. It's just a nice software/laptop based scanner.

Ok...I just put in the correct plugs and it seems to be running better but it still has that balking feel when it is at low rpms. Also while out driving it, I stopped for a few at a friends house and when I left, it wouldnt idle up with the throttle. When I gave it gas, it would try to die so I kept goosing the throttle until I got it going and took it home. ( have to admit I was messing with the harness, uncrossing wires and plugging them back in C1&C2 before I left)

EDIT: Maybe a bad O2 sensor?
EDIT 2: I just unplugged the O2 sensor and it seems to run a bit better. Still balks. Also wondering if any of this is caused by running no EGR and stock 98 program. Just waiting on wheels and tires so Ryan can program in compensation for the tire hight.
Any thoughts?

Steve

[This message has been edited by JumpStart (edited 09-11-2011).]

What are your scans showing? If you forgot to change out the plugs to the correct ones then what else did you possibly forget? Double check to insure all ur wires are going to the correct coils and did you clean the injectors before installing them?

quote Originally posted by MstangsBware: What are your scans showing? If you forgot to change out the plugs to the correct ones then what else did you possibly forget? Double check to insure all ur wires are going to the correct coils and did you clean the injectors before installing them?

I dont have any way to scan for codes and I double checked the wires, However I never cleaned the injectors. what the best way of doing this other than injector cleaner in the fuel?

Thanks, Steve

quote Originally posted by JumpStart: I dont have any way to scan for codes and I double checked the wires, However I never cleaned the injectors. what the best way of doing this other than injector cleaner in the fuel? Thanks, Steve

You need to invest in a scanner as it is one of the first MODs everyone that does the 3800 swap needs to invest in...It can save you a hours of guessing....I always use carb cleaner and compressed air to clean the injectors before I install them...It is not a complete cleaning but have never had a dirty one cause issues yet....

should I get a plain OBD2 scanner from the parts store ( around $80) or is there a data link cable I can use with a laptop and a program?

quote Originally posted by JumpStart: should I get a plain OBD2 scanner from the parts store ( around $80) or is there a data link cable I can use with a laptop and a program?

Find a scanner that runs a program on the computer so you can log the data and then look at it....I also recoommed a full time scanner that stays in the car for live data...

Ok, Thanks. Ill check and see what I can find.

Steve