95 Suburban, intermittant rough idle

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

AbdMalik - 22 Sep 2004 00:30 GMT

hi,
i have a 95 suburban 1500 5.7l with 130k miles. it tends to idle
roughly and give off a foul odor when i am at a stop. when i drive
off, it seems to be ok but when i come to a stop again the rough idle
returns. i noticed that it rough idles only after warming up. also, if
i shut the truck off, then soon start it up again, the restart is
difficult unless is press the gas pedal while starting. sometimes when
i come to a stop, the idle corrects itself temporarily but soon
becomes rough again.
i hope that i described the problem clearly and if there is anyone who
has an idea what the problem is, please respond.
thank you in advance,

abd

Reply to this Message

GMC Gremlin - 22 Sep 2004 00:37 GMT

Any codes?
Sounds like a dirty EGR valve. It's a big mushroom-looking thing. It allows
a small amount of exhaust gas into the combustion chamber at high speeds to
reduce combustion temp to manage NOx's. When it gets stuck open, it allows
exhaust into the chambers at all times and can cause a rough idle. You can
either buy a new one or clean your existing one. If you remove yours you can
plug the hole, to CHECK if it solves the rough idle. Do NOT just plug it.

GMC Gremlin

> hi,
> i have a 95 suburban 1500 5.7l with 130k miles. it tends to idle
[quoted text clipped - 10 lines]
>
> abd

Reply to this Message

Bret Chase - 22 Sep 2004 01:45 GMT

>:|Any codes?
>:|Sounds like a dirty EGR valve. It's a big mushroom-looking thing. It allows
[quoted text clipped - 5 lines]
>:|
>:|GMC Gremlin

pull the vacuum hose off of the EGR valve and stick your finger over
it. if at idle you feel vacuum, replace the solenoid as it's leaking.
if not, plug the EGR valve end of the vac line into the vent ( this
will prevent weird vaccum leak symptoms for the following test.) and
drive the truck around. if it's better it's the valve, if it' not
better look else where. you can pull the valve and clean it with
brake cleaner... I'd try that before dropping 80 bucks on a new one.

hth,
Bret

>:|> hi,
>:|> i have a 95 suburban 1500 5.7l with 130k miles. it tends to idle
[quoted text clipped - 10 lines]
>:|>
>:|> abd

Reply to this Message

AbdMalik - 22 Sep 2004 11:43 GMT

thank you for the replies guys. i have no codes because i do not know
how to get them. is there a scanner or something that i need to
retrieve the codes?
abd

Reply to this Message

GMC Gremlin - 23 Sep 2004 02:34 GMT

IIRC it's either 95 or 96 that they still had the OBD I system with the OBD
II connector, so you need a shop-quality scan tool, bout $2,000.

GMC Gremlin

> thank you for the replies guys. i have no codes because i do not know
> how to get them. is there a scanner or something that i need to
> retrieve the codes?
> abd

Reply to this Message

\ - 22 Sep 2004 05:12 GMT

> hi,
> i have a 95 suburban 1500 5.7l with 130k miles. it tends to idle
[quoted text clipped - 10 lines]
>
> abd

Sounds like your FPR (fuel pressure regulator) is on it's way out and
causing it to load up when you're idling and causing the rough starts. The
other folks who suggested EGR might be correct, but having to crack the
throttle to start it isn't a symptom of a crapped out EGR.

Doc

Reply to this Message