1999 4.3 misfiring

gmoncrief
0

Asked by gmoncrief Jan 05, 2009 at 12:22 PM about the 1999 Chevrolet S-10 2 Dr STD Standard Cab LB

Question type: Maintenance & Repair

I'm running out of ideas on a problem with my 99 S10 4.3
The truck will start and idle fine however as soon as you feed a little gas it starts to miss.
Giving it even more gas is either covering up the misfire or it is clearing and seeems to run better.
I've just replaced cap/rotor wires and plugs.
The problem seems to get worse whenever it gets even slightly wet/humid.
I had Cragen hookup a analyzer and it gave a "random misfire" error code.

Does anyone have an idea of where to look?
Thanks Greg
gmoncrief@hotmail.com

5 Answers

Michael McGrail
5,545

I would look at replacing your coil, moisture will commonly mess them up if they have a crack in them. If the coil is going out, the more you require from it, the more the engine will miss. It would create the code given. That would be my best educated guess from the information you gave.

1 out of 1 people think this is helpful.
Danny Wang
2,595

Just as a possibility I may also suggest trying a MAF cleanner, it should be about $8 a can. If it improve significantly, then I recommend replacing the MAF. Even though the frequency could be operating within specification, if it does not change as quickly as load on the engine changes, the engine may not be able to fire at the right time.

1 out of 1 people think this is helpful.
Jeremy Prchlik
45

your problem is a bad throttle position sensor, i had the exact sme problem, changed everything out but that sensor and it finally stopped doin that once i replaced the TPS. same exact conditions, whebn it got humid or after a rain it ran like shit lol

3 out of 3 people think this is helpful.
chevyfan88
0

I have this same problem with my 99 s10 4.3. the code reader says miss fire cylinder #2... so I replaced wires, plugs, distributer cap and rotor. after 2 days this problem got worse. again I read the codes and it read the same code, cylinder #2. good old GM I guess

FRANKENTRUCK
20

I know this an old thread, but seen alot of questions across these forums while searching for an answer to problem that seems to be irritating all of us 4.3 vortec owners. "The dreaded mystery coldstart misfire." I like many others had the shudder between 1500-1800 rpms until the engine came up to operating temperature. I just found the root of all evil hiding under the EGR valve. Removed EGR to clean and realized there was a blow by in the gasket. Removed gasket and noticed it was on the topside and underside of the gasket. Scraped the remainder off, cleaned the surface, and installed new gasket with original EGR valve. Instant success! I can see why people got rid of the issue when replacing spider injector because they probably removed and reinstalled new gasket when replacing EGR. Less than an $2.00 fix compared to the $300.00 cost of new injectors.(I still need to replace injectors as mine has over 300,000 miles on original but thats another project) Also remedied some annoying valve chatter. Worked for me...hope this information helps others!

2 out of 2 people think this is helpful.

Your Answer

Add photo

Related Questions

S-10
Looking for a Used S-10 in your area?
CarGurus has 1,878 nationwide S-10 listings starting at $1,450.
ZIP:

Search Chevrolet S-10 Questions

Chevrolet S-10 Experts

#1 Andrew Olsen
Andrew Olsen
Reputation 780
#2 John Saffrahn
John Saffrahn
Reputation 470
#3 Trebor66
Trebor66
Reputation 420
View All

Related Models For Sale

Used Ford Ranger"
364 Great Deals out of 6,788 listings starting at $700
Used GMC Sonoma"
24 Great Deals out of 608 listings starting at $1,795
Used Chevrolet Silverado 1500"
2,498 Great Deals out of 170,889 listings starting at $650
Used Toyota Tacoma"
689 Great Deals out of 23,277 listings starting at $2,199
Used Ford F-150"
2,919 Great Deals out of 154,329 listings starting at $1,500
Used Dodge Dakota"
170 Great Deals out of 4,365 listings starting at $2,395
Used Nissan Frontier"
379 Great Deals out of 21,225 listings starting at $2,390
Used Chevrolet Blazer"
24 Great Deals out of 1,870 listings starting at $1,900
Used GMC Sierra 1500"
1,076 Great Deals out of 59,546 listings starting at $1,999
Used Dodge Ram Pickup 1500"
846 Great Deals out of 14,520 listings starting at $1,900
Used Jeep Wrangler"
1,189 Great Deals out of 49,382 listings starting at $1,800
Used Chevrolet C/K 1500"
1,033 listings starting at $3,900