almost stalling, but not?

[chevyguy93]

okay so ive had this problem for a while, but i have a little more info this time. Almost every time I'm out driving in my car, (it happens atleast once) the engine seems to drop in rpms, almost like it shut off, but then it started back up to normal. Sometimes when you put it into reverse, it happens, and then you give it gas to back up, it wants to stall. And then other times it happens when your just sitting at a stop sign. Today i was coming home in the dark, and it did it as I was pulling into my driveway. I noticed that as it happened, my headlights went very dim, almost as if they were completely turned off, and then turned back on again as everything went back to normal. ... whats going on?

[Luis F]

did u check ur battery.?

[chevyguy93]

battery is brand new. i even replaced it a few months ago, and i had the problem before i replaced it too.

[jdl]

Were there any codes? If it seems throttle related, check the TPS. If idle related, clean the throttle-body and check the iac. When was the last time you replaced the fuel filter? Is the fuel pressure ok?

Sometimes, performance mods can cause problems.
Does this have an automatic tranny?

[chevyguy93]

No there werent any codes unfortunately. I checked the TPS a few months ago with my meter and it seemed like it was working alright. How would I go about cleaning the throttle body? And I was thinking bout replacing the IAC, but wasnt sure what the cost would be. I already replaced the o2 sensor. And I replaced the fuel filter in the summertime, and the fuel pressure should be okay.

And its an automotatic transmission. thx for all the help sofar

[JStumpalump150]

what is the idle rpms?

[chevyguy93]

i have no idea. i dont have a tach. it seems pretty normal tho.
one time this happened, and the rpms jumped up high and stayed for a 30 minute trip in the city. It was hard on the transmission because it couldn't downshift properly while it was idling high.

also. last night when it happened, it happened just after i turned the steering wheel all the way to the right. The engine struggled for a second because i had it turned so far. Once i straightened out, thats when it acted goofy.

[chevyguy93]

okay so i got a lil more info. today it happened again. except this time it completely stalled. I was in a parking lot, and was leaving. when you leave the parking lot there is a steep ramp that you drive down. I was going down it and stopped, and then the car struggled for a few seconds and then stalled. I remember it happened a few months ago in the same spot. This is making me think its a fuel related problem. ?

[chevyguy93]

it happened AGAIN grr. in the middle of the pay station in a busy parking garage. it stalled. over and over. i had to give it gas to keep it going. I went and bought throttle body cleaner. I took out the iac valve (which was all black and gungy) and cleaned it really good. along with the throttle body. Hopefully this helps

[chevyguy93]

okay so nothing i did sofar has fixed the problem. I'm beginning to think that one of the cylinders is misfiring or something. A few weeks ago i replaced my plug wires and it didnt make a difference. My spark plugs are only a couple months old. Plug 1 and 4 were extremely hard to remove, while 2 and 3 were easy. Don't kno if that says anything or what. And they looked pretty clean when i removed them. any thoughts?

[450HP]

My 98 Cav is having a similar issue... tonight it finally threw a code - P0404 -
EGR valve pintle sticking open.

Might want to check your EGR valve... I'm looking to see if there is a way to
clean mine.

Good Luck!
Scott

[chevyguy93]

thanks for the info. I was somewhat thinking of the egr valve, but wasnt quite sure. I already replaced the iac and tps, and it hadnt made a difference. There isnt really much to replace on these cars, so its kinda confusing as to what the problem is. As for cleaning it, i think throttle body cleaner can be used, but i'm not 100% sure. I'll probably take mine apart on the weekend, get a new gasket for it, and clean it good. Hopefully it will cure the problem.

[chevyguy93]

Alright. So my father and I went to the scrap yard yesterday and got ANOTHer iac valve, tps, a map sensor, and an egr valve, and threw it all in there. The car drove fine for a few minutes, but when i pulled off the highway into a parking lot, it started idling very low and i had to keep giving it gas for it to stay going. And also, when you brake to slow down, as you get slower, the engine begins to shake, and the whole car shakes. We put the origional map sensor on because we noticed the numbers were different. Took it for another drive, same thing. I pulled into my driveway which is slightly slanted upwards, and put it into park. When i did, the rpms dropped, came back up, and then it just kept surging high and low. We popped the hood looking for any vacuum leak, but couldnt find anything. No matter what we do, we still have this problem. I am somewhat thinking its a clogged injector? Would it have the same affect?

[muff34]

have you checked your catalytic converter to see if it`s pulgged ?

[chevyguy93]

=) i dont have one. just a muffler