Lets try to keep this a thrad about hesitation off idle and not an end-all hestiations thread.

 

ok have any of u scanned ur cars?i did so last week with a tech 2 and found out some interesting info.at wot the timing would drop as low as 17 degrees and spark knock was thru the roof.im getting a popping almost off an idle when i floor it and then at about 4500 and 5100.tech 2 showed no spark at those points.but only when under load.same if i have ac on and just try to pass someone it does it.

also has anyone tried seafoam or gm top end cleaner?im going to this week and see if it helps me any as i have 130,000 miles on the clock.

btw--i have a new coil,wires,plugs,opti,o2's and the egr delete.

i have also noticed that lt1's r not big fans of platinum plugs as i have gone thru 3 sets this yr.im switching to ac delco rapid fires this week also.

 

I WOULD CHANGE OR CHECK YOUR O2 SENSORS. When i scanned my car they looked fine. But i replaced them any ways and my bad idle and hesitation went right away. GOOD LUCK.....

 

i replaced them with boschs last week.i just did the firework check and not suure or not about my outcome.the whites of the plugs were glowing when the sparked but the wires themselves were not.also where the coil wire plugs into the coil was too.any ideas?

 

hey heath! Have you had a fuel pressure gauge on the fuel rail and watch it when under load as you try to go above 5000 rpms?

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'97SS, More Performance 396, AS&M cold air, Grotyohann LT, SLP 2ODL muffler, Magnacor, PCMFORLESS PCM, LS1 twin piston calipers, KVR crossdrilled and coated rotors, SLP stage II w/ KYB AGX, 6M, Star Stage II.

 

i have not but the dealer has checked that and said it was fine..

now they have exhausted the techs ability or patience and they have assigned it to a different tech, hes kinda a guru with these things god do i hope he nails it it would be nice to have it back my big *** truck is sucking gas..

 

hey guys i just got some interesting findings--try and swap out a maf with a car u know runs strong.i was suprised at how much better the car ran.next is the map sensor to try and cure the rest of my timing.i know if i unplug the maf the car dies and it should still run in speed density mode.anyone else have similar findings?

 

Check your radiator and coolant level. Also make sure to bleed it properly. I had the same problem after a new radiotar was installed. I took it back and had them bleed it better. Haven't had a problem since.

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Jet Black '93 Z28 M6
K&N FIPK, BBK Shorty Headers, Flowmaster, Hurst Shifter, Interior Light Switches, Indiglo Race Pedals, Indiglo Gauges, Sequential Tail Lights
White Z28 and 5.7L LT1 decals

Stereo:
Alpine 7864 CD Player
MTX 1600W Bass Amp
Kenwood Excelon 1200W Amp
(2) 12" Polk Momo Subs
Polk Momo MM465 speakers w/ tweets and crossovers

 

i remember one time i was talking to a mechanic that was working on an LT1 firebird and he said it had a bad stumble off idle and he said he replaced the MAP sensor and that helped the stumble alot but he said he thought the rest of the stumble was caused by the opti since the waterpump had just gone out. So you can take that for what its worth.

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1995 Z28 m6
FIPK, !CAGS, !AIR, !EGR, !MAF descreen, !Cat straight pipe, Hurst Billet Plus shifter, TB bypass, LT4 KM, Airfoil, Borla catback, 160 stat', SLP shorties

 

i have already replaced opti and map.
have unplugged maf. and swapped it. no help??

how could antifreez cause anything ?
just wondering????

thanks

heath


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94 T/A LT1 A4
SOME MODS,KINDA QUICK
times- C-YA AT THE TRACK!!

 

I agree that the anti-freeze should not cause your problem...air in the system will have it run hot. Has the mechanic checked to see what the PCM is reading as coolant tempt? our instrament gauge takes the temps off the cylinder head and the PCM reads it off a different sensor in the water pump. The PCM makes alot of it's fuel trims and timing off the coolant temp sensor the PCM reads. just another idea. Has the mechanic placed the car on the old fashion ignition scope? If not, he may want to to verify you have proper spark up the rpm band. what kind of spark plug you using?

 

CARL im not sure if the dealer has put it on a scope i know they have one ive used it before. i worked there for 5 yrs or so. i know the tech that helped me w/ the head took it to his shop and said he scoped it and could find no bad spark or missfires.

as per plugs im using the delco platinums??

 

The blue around the plugs is called "Coronal Discharge" and it is normal. It is the result of ionization of the air around the plug due to the high voltage present. It is a normal condition. If you get an acutal miss associated with an arc, then you have a problem.



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1997 Z28 MM6 Moroso CAI, Flomaster American Thunder, Taylor, Air Foil, SLP Headers, Crane Ignition, MAF, HPPIII, 4:10's, Summit Girdle, Drilled Rotors,
13.75@ 100.98 MPH
2.055 60'

No New Times With Gears....yet.

 

heath, how about the coolant temp sensor?

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'97SS, More Performance 396, AS&M cold air, Grotyohann LT, SLP 2ODL muffler, Magnacor, PCMFORLESS PCM, LS1 twin piston calipers, KVR crossdrilled and coated rotors, SLP stage II w/ KYB AGX, 6M, Star Stage II.

 

a hesitation during acceleration most likely has to be:

vacuum leak

ignition timing off

ignition system faulty

fuel injectors

or fuel pressure

just my $0.02

good luck

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96 Z28, M6, Moroso CAI, Paul Barry hi temp coated SLP headers, Accel Extreme 9000 Heat Reflective wires, Borla cat-back, Pro 5.0 shifter, Lou's Short Stick, BMR STB & SFC, SLP Bilstein shocks, T/A rear cover, Dunlop SP Sport 5000 tires