Lets see if we can tentatively diagnose this.. stumble at low rpms

Myco

Myco

Dedicated LVC Member
Joined
Nov 28, 2008
Messages
913
Reaction score
8
Location
Houston
Car has been sitting for a while. It was ran often to in and out of the garage but not on the street.

before the car was parked the spark plugs were new, the fuel filter was fairly new. What I'm thinking is the crap in the gas has clogged the filter. Any other thoughts on this?
 
That would be my first thought...varnished gas...if it's varnished..drop tank, CLEAN tank,clean pump, reinstall, add gas, replace filter, retry
 
, i don't know you said only 9 months, mine sat for over a year and it would start up no problem even at 40 degrees, andit only had a quarter tank too
 
danny_holtermann said:
, i don't know you said only 9 months, mine sat for over a year and it would start up no problem even at 40 degrees, andit only had a quarter tank too
Click to expand...


Let me rephrase. It starts fine but when I git the gas... at low rpm's it stumbles. Prob. between 2-3k it stumbles a bit and then accelerates great.

If I stay off the gas it idles fine.
 
m_maker said:
bad coil(s), bad boot(s), bad spark plug(s).
Click to expand...

new boots on one side... other side was inspected when the new boots were put on but good call. Hood was off for quite a while. I'll check them.
 
IAC? (idle air control valve)

And check fuel pressure and fuel regulator - but thats a long shot right now. But I say checking fuel pressure is like doctors checking blood pressure as standard part of a visit.
 
unity said:
IAC? (idle air control valve)

And check fuel pressure and fuel regulator - but thats a long shot right now. But I say checking fuel pressure is like doctors checking blood pressure as standard part of a visit.
Click to expand...

It's very intermittent. It will idle at a light fine and then start stumbling badly for a couple seconds and then start idling fine again. under power though it's always a bad miss.
 
Ya... sounds like IAC to me them. If they gum up they do not respond properly to throttle movement. And if its never been done, it just a good idea to replace a $40 part that usually WILL go bad. If you have a 97/98, its a cat walk to replace. If not, its a pain.
 
unity said:
Ya... sounds like IAC to me them. If they gum up they do not respond properly to throttle movement. And if its never been done, it just a good idea to replace a $40 part that usually WILL go bad. If you have a 97/98, its a cat walk to replace. If not, its a pain.
Click to expand...

sorry for not saying so before but IAC is new, but I do understand it doesn't rule that out.

car's at the shop now so can't work on it.
 
I put new gas in it and it's still stumbling pretty badly. Just got it home from the shop. had a 1/4 tank of gas in it and I put in 2/4 of premium gas and drove it 5 miles home. Thinking maybe the good gas didn't get to the engine.

Also, I put in 1/3 can of seafoam in it yesterday before I took it to get it inspected, but this problem was happening before I put the seafoam in it.

edit: also I just got it inspected and the inspection said It had no misses and it was stumbling badly when I went in. This makes me think it's the gas or filter.

Makes me wonder if driving it 5 miles on the new/mixed gas in there was enough to get the new gas into the engine. Maybe driving a bit more would help.
 
Get a fuel pressure reading. Could be a coil (think that was mentioned) causing a slight miss.
 
I had a new OEM coil pack go bad in a month. Drove me nuts. Could not solve it, after all they were new! The miss was not a full blow miss, so no code.
 
unity said:
I had a new OEM coil pack go bad in a month. Drove me nuts. Could not solve it, after all they were new! The miss was not a full blow miss, so no code.
Click to expand...


Yea, under 2k rpm it has no torque and of course at idle it feels like it has a heavy duty cam. Don't think it's the gas.

Going to let it cool and pull the spark plug covers and check the COP's and the rubber condensers. If it's not that I'll move on to the spark plugs. Don't know why letting a car sit would make a plug not work though. They were new when I started the painting and I let it run every once in a while to get it in and out of the garage.
 
Did you let it get up to temp or just move it. In 2002 my company had a Toyota or something basically go bad, it was BRAND new. it was from moving in and out of the installer bays almost everyday for a few weeks. It needed new plugs and some other stuff.
 
Check your plugs, check for proper gap...check for vacuum leaks...sounds more like a vacuum problem IMHO
 
Sapperfire said:
Check your plugs, check for proper gap...check for vacuum leaks...sounds more like a vacuum problem IMHO
Click to expand...

I was going to spray some mass air flow cleaner over the hood and see how that works but after looking around I'm out. Just got the car cool so I'll check the boots and coil packs first.
 
I just took out the back driver side plug and the boot has junk all over it and the plug did too. I blew out the plug hole BEFORE I took out the plug but now when I look in there it looks like a bit got in the cylinder. CRAP

There was serious crap in that plug hole... I have pictures hold on.
 
DSC01505.jpg

DSC01506.jpg

DSC01507.jpg

DSC01508.jpg
 
around the base where the spark plug goes in there is a bunch of junk. But without the plug in there I don't want to try to clean it out.
 
You must log in or register to reply here.

Members online

No members online now.
Total: 366 (members: 0, guests: 366)
Back
Top