1998awdastro

1998 Chevy Astro AWD
kept throwing a mis-fire code as it was having trouble starting worst in wet weather, 2weeks ago i was finally able to put new plugs and wires in it and that cured the starting problem and mis-fire, cap and rotor still looked good and cleaned them up and put them back on, engine has 126,000 miles no smoke no noise runs really good. now for the problem
and it was alittle chilly out this morning and started it and went ahead to drive it to bus stop, it still seams like its missing when the trans gets ready to shift to second i feel the engine is cutting out, power curve higher before it shifts to second, then its fine ( i feel tho if i push it like the first shift it will still cut out) its alittle better when its warmed up but you can still feel it.
also when your on the hi-way traveling 60 it seems to be fine but when you increase the speed to say like 70 it feels like a bump another bump faster you go the more it does it. like a cut out in the engine.. its getting worst now and i need the van..
March 2010 i put in a new fuel pump assembly and fuel filter this last feb 2011 i put in new cap and rotor..
any ideas?pulling my hair out...... not throwing any codes.... could the coil be going bad?

Mj

1998awdastro

Could it be the cheap cap and rotor i put on it awhile back........i noticed it doesnt do it all the time, and when on a load (like going up a steep hill) i dont notice it at all...... then other times it acts up....... any clue? anyone?

Mj

T.Neff

You need to clear all the previous codes by disconnecting the battery.Then the first code is the fault.

Fuel pumps like "Airtex" are junk that don't run on factory specs and don't last very long.Delco used to be the suggested brand and even those have cross matched pumps where the PSI spec isn't what it should be,but the volume spec is.Delphi still builds the proper PSI/volume pumps and is recommended.So on a cheap pump,it is possible it has gone bad already.Do a fuel pressure test.You want to do the fuel pressure test while driving too.
Do the key on and off fuel pressure test for the fuel regulator.

The cap and rotor is Delco all the way.While your in there-knock out the screen at the bottom of the dizzy.They get clogged and with the hot and cold temp create condensation inside the dizzy.Same holds true for the plug wires.Could be true they don't leak at a idle,but once the RPM's raise they do and miss fire.

Coils generally either work or not.

Check the battery's condition and charging system.It should be checked at the battery terminals.Like 12.4 without the engine running,and 14.3 or more while running.Also load test it.Why??.Well the ignition system/ECM relies heavily on those voltages to be in spec and if not will create all kind of havoc.


Bottom line.You got to build a foundation of known parts that eliminates that as a issue.And I am not saying for you to shot gun parts in a guess as to what is wrong,but it does get more complicated to find the problem once you have installed the cheaper suspect parts.Fact is they are NOT the same or good as..................

1998awdastro

OBD ll Scanner recordings
(idling in driveway after driving 15 miles)
ABSLT (%) 0.0
ENG SPEED (RPM) 655
CALC LAOD(%) 3.1
MAF(LB/M) 0.73
MAP("HG) 9.7
COOLANT(F) 156
IAT(F) 81
IGN ADV 19.5
ST FTRM1(%) -4.7
LT FTRM1(%) -5.5
ST FTRM2 (%) -3.9
LT FTRM2(%) -8.6
FUEL SYS 1 CLSD
FUEL SYS 2 CLSD
02S11(V) 0.135
ST FTRM11(%) -88.3
02S13(V) 0.855
02S21(V) 0.105
ST FTRM21(%) -87.5
PTO STATUS DISE
THROWING CODE P0300 MISFIRE STILL..........

CHARGING SYSTEM IS UP AND IN GOOD RUNNING STATE...

DRIVING IN REG DRIVE (NO oVERDRIVE) man can you feel it missing................ i am thinking it comes down to cap and rotor, should put a delco cap or upgrade to the one above.............

thanks for anyhelp

Mj

kevinkpk

Sounds to me like the cap is at fault. It could have a small hole in it, that would cause your symptoms

T.Neff

Not sure if you didn't had it at operating temp or not,but it needs to be at 195 to work correctly.Nothing less.

1998awdastro

Last two and half years of owning it hardly ever see's anything above 190 .. but true. i noticed a imperfection in the cap and i second quessed it.... so i will try that end of next week....... it did have a problem i didnt notice till feb when i put the cap on that one of the ears was broken, i have it fixed correctly now thank god for Plastic epoxy! drilled and tapped and is now tight....... will let everyone know how i made out......... thank you.........
Mj

1998awdastro

Yup that cured the problem, i shoudl have listened back in Feb with what everyone was saying! the alum inserts just couldnt handle the voltage, i picked a Accel cap and rotor (40 bucks) and it has brass inserts! that can handle 60,000Volts and it runs aton better!! infact it runs better now then when i bought it 2 and 1/2 years ago.... thank you for all your help!

Mj

T.Neff

There is a screen at the bottom of the dizzy that gets plugged and creates condensation.The fix is to knock out that screen.

jelectrico

Im glad the cap and rotor did the job.
I was going to suggest the same but the guys were already commenting.