1998 Chevy Silverado Question for: Rasmataz

Tiny
DCS1998
  • MEMBER
  • 1998 CHEVROLET SILVERADO
Engine Performance problem
1998 Chevy Silverado V8 Two Wheel Drive Automatic 132K+ miles

This is the first of several questions that I will Prob. Ask of you over time about this truck.
First a little history. This truck started leaking coolant at the quick connect for the heater and has been hot before.
A year ago, it started losing coolant (found it coming out the tail pipe. Used some Bar's Leak (for head gaskets and such) and it stopped using coolant. A day after this long and drawn out deal of the Bar's Leak, engine started idling pretty high (2000-2500 and now 3000). I still drove it a little just had to ride the brake when in a 30mph zone.
Had a fuel pump quit and replaced that.

Now to the meat:
I had read (by you I think)about spraying TB cleaner around the intake to check for leaks. I did that, and the engine sped up. That means there is a leak, correct? It was on both sides from front to back. I figure it burnt up the o-ring looking gasket when it got hot.
I went today and got a complet set of gaskets for the intake (top and bottom).

Im getting 4 codes (btw thanks for everything about code readers, their a great thing to have around) P0300, P0300pendind, P0507 and P0507pending.

Do you think all this trouble (random mis fires and high idle) could be caused by bad gaskets? Or do I need to get the gaskets in place and plain on making other repairs also?
David
Do you
have the same problem?
Yes
No
Sunday, April 12th, 2009 AT 7:00 PM

13 Replies

Tiny
RASMATAZ
  • MEMBER
Try erasing the codes again

Do you think all this trouble (random mis fires and high idle) could be caused by bad gaskets? Its leaking vacuum and the xtra air is not being measured by the MAF sensor.

Misfires can be caused by worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open, dirty fuel injectors, low fuel pressure, or even bad fuel.

A Random Misfire code usually indicates a vacuum leak or bad gas.
Was this
answer
helpful?
Yes
No
Sunday, April 12th, 2009 AT 7:40 PM
Tiny
DCS1998
  • MEMBER
Side question and statment:
You mentioned "bad gas".
My Father had a small engine repair guy tell him, "Dont use gasoline with 10% Ethanol in it! Weedeaters, chainsaws and lawnmowers aint made for it!"

Could the same be true for trucks and cars as old as mine? Could that have helped mess up my fuel pump and get the last life out of that o-ring lookin plentum gasket? Just wonderin.
Was this
answer
helpful?
Yes
No
Sunday, April 12th, 2009 AT 7:58 PM
Tiny
RASMATAZ
  • MEMBER
Could the same be true for trucks and cars as old as mine? Could that have helped mess up my fuel pump and get the last life out of that o-ring lookin plentum gasket? Just wonderin. I don't think it wiil affect the fuel pump-I'm concern about the gasket you mentioned get that squared away and then we'll go from there.
Was this
answer
helpful?
Yes
No
Sunday, April 12th, 2009 AT 10:10 PM
Tiny
DCS1998
  • MEMBER
Ras Dude,
Im not quite finished removing the intake and all yet, but wondering if you have the torque values for the intake, plentum and TB handy?
Was this
answer
helpful?
Yes
No
Thursday, April 16th, 2009 AT 3:51 PM
Tiny
RASMATAZ
  • MEMBER
What engine is this 5.0 or 5.7?
Was this
answer
helpful?
Yes
No
Thursday, April 16th, 2009 AT 3:56 PM
Tiny
DCS1998
  • MEMBER
5.0L (305cid)
Was this
answer
helpful?
Yes
No
Thursday, April 16th, 2009 AT 4:00 PM
Tiny
RASMATAZ
  • MEMBER
Upper intake Step1 44inch lbs
Step2 88inch lbs

Lower intake Step1 27in lbs
Step2 106in lbs
Step 133in lbs

Lower intake tighten sequences:


http://www.2carpros.com/forum/automotive_pictures/12900_intake_3.jpg



TB no torque specs-I guess you play it by ear
Was this
answer
helpful?
Yes
No
Thursday, April 16th, 2009 AT 5:39 PM
Tiny
DCS1998
  • MEMBER
Thank you for the torque values Rasmataz

I have replaced the top intake gaskets.
Cleared the codes.
Truck still idles very high (2500+)
Drove it about 20 miles.
Getting codes P0300, P0300 pending and P0121 pendind. (There has been no P0507 like before, shown up yet)

I picked up a new set of wires the other day, and plan to install them with a new set of plugs.

Im still a little worried as to why the idle is so high. Any ideas?
Was this
answer
helpful?
Yes
No
Monday, April 20th, 2009 AT 12:33 AM
Tiny
RASMATAZ
  • MEMBER
A Random Misfire P0300 code usually indicates a vacuum leak or bad gas.

The high idle have you cleaned out the IACV? If not do so.
Was this
answer
helpful?
Yes
No
Monday, April 20th, 2009 AT 1:54 PM
Tiny
DCS1998
  • MEMBER
Just put in a new one and cleaned the bore.
After warming up it idles around 3K rpm's (in drive it will come down to 1000 rpm's)

Havent installed the new plugs and wires yet.

Thanks for all the help youre giving me Ras.
Boy when I get that income tax check, youre first on my list!
David
Was this
answer
helpful?
Yes
No
Monday, April 20th, 2009 AT 7:19 PM
Tiny
RASMATAZ
  • MEMBER
You probably need to reset the idle air control valve or get the EEPROM programmed
Was this
answer
helpful?
Yes
No
Monday, April 20th, 2009 AT 9:14 PM
Tiny
DCS1998
  • MEMBER
Now you just went over my head!

I dont know how to reset an IACV, and as far as the EPROM? Where would (or could) that EPROM stuff take place at? Dealership? We have a few places around town that say they are up on all the latest stuff, maybe they could do it?
Was this
answer
helpful?
Yes
No
Monday, April 20th, 2009 AT 10:02 PM
Tiny
RASMATAZ
  • MEMBER
Keep driving it till the computer relearn itself. If it continues you need to have the EEPROM programmed-Dealer or whoever that can do it.
Was this
answer
helpful?
Yes
No
Monday, April 20th, 2009 AT 10:44 PM

Please login or register to post a reply.

Recommended Guides