95s-10 hard starting when warm

my blazer starts like a dream when it is cold. if I trying to start 20 min after shut off, if i dont give it some gas it wont start and sputted out, sometimes not starting at all till a minute later. Sometimes problem seems totally intermittent. I have replaced plugs, wires, cap, rotor, coil, coil module, both HO2 sensors, camshaft position sensor, and EGR.Truck also has new starter, alternator,and batterry.
Service engine codes i am getting when the truck don't start are
Inigtion control {IC} has hogh voltage
HO2 sensors cross counts to few

Truck engine code is {w}

Can anyone help? Thanks!

More than likely you have a leaking CPI unit and once it heats up the diaphram leaks more causing excessive fuel dump which makes it harder to start.

Also, stop pressing the gas to start the engine, it only floods the cylinders.

You never touch the gas pedal on a fuel injected vehicle.

Pressing the gas doesn't really do anything to a fuel injected engine. (this can easily be shown by pulling a poppet or an injector on a regular car and pressing the gas. Nothing will come out as the car is not on, the fuel pump isn't on and the throttle plate doesn't affect what's pulsed to the injectors.

Now, even pressing it during start while you're cranking the engine won't do anything as the computer is only reading enough of an air/fuel mix to kick the engine over.

When you step on the gas pedal, the throttle valve opens up more, letting in more air. The engine control unit (ECU, the computer that controls all of the electronic components on your engine) "sees" the throttle valve open and increases the fuel rate in anticipation of more air entering the engine. It is important to increase the fuel rate as soon as the throttle valve opens; otherwise, when the gas pedal is first pressed, there may be a hesitation as some air reaches the cylinders without enough fuel in it.

http://auto.howstuffworks.com/fuel-injection2.htm

there is almost no air coming in regardless when the engine first kicks. once it catches it then goes into full operation... This can also be shown in the ECM programming (see s10wildside for more info) as well as a general scantool.

Also, stop pressing the gas to start the engine, it only floods the cylinders.

You never touch the gas pedal on a fuel injected vehicle.

If i dont press the gas the car wont start! i was wondering if maybe my cranksharft sensor is bad not giving accuarte rpm because in the chevy manual inigtion control enguages at around 400 rpm thus press the gas would raise engine rpm causing ingtion control system to operate

there is almost no air coming in regardless when the engine first kicks. once it catches it then goes into full operation... This can also be shown in the ECM programming (see s10wildside for more info) as well as a general scantool.

i do have a gerneral GM scan tool called tech 2 i just don't understand all the readings my father used to be the person that would help me with these problems

is it a scan tool for obd1 obd 1.5 (i think thats what you have being a 95) or obdII?

Let me know your findings.My 98 does this sometimes not as extreme as yours though.When mine is warm sometimes it takes like 4-6 seconds before it fires,when it's cold it fires right up.

is it a scan tool for obd1 obd 1.5 (i think thats what you have being a 95) or obdII?

I am not sure what version code it is, but my scan tols reads it the codes i get are
P0172 fuel trim system rich bank 1
P0300 engine misfire
P1133 HO2S cross counts bank 1 sensor 1 to few
P1221 fuel pump feedback circuit low voltage
P1351 ingition control(IC) circuit high voltage
will that help find what code it is

those are the codes... Sounds like an injector problem... You actually have the 1st revision ODBII. But by all the codes set, it looks like you're dumping fuel. Pull the upper plenum and check for washing.

is it a scan tool for obd1 obd 1.5 (i think thats what you have being a 95) or obdII?

I am not sure what version code it is, but my scan tols reads it the codes i get are
P0172 fuel trim system rich bank 1
P0300 engine misfire
P1133 HO2S cross counts bank 1 sensor 1 to few
P1221 fuel pump feedback circuit low voltage
P1351 ingition control(IC) circuit high voltage
will that help find what code it is

Remove the top vortec name plate and the round black IMTV valve underneath it and take a strong flashlight and shine it down into the plenum and look for washing and the strong smell of fuel.

Washing will be shiny metallic spots whereas it should be black and dirty.

Seeing that you are getting the rich codes, you injector is probably dumping fuel into the cylinders.

You need to get this checked out ASAP.

Also, pull the oil dipstick and check to see if the oil is really high and if the oil on the dipstick smells of gas.

Blazer,any idea why mine would do it?I don't have the nice Vortec cover though.

those are the codes... Sounds like an injector problem... You actually have the 1st revision ODBII. But by all the codes set, it looks like you're dumping fuel. Pull the upper plenum and check for washing.

If I pull the upper plenum and find washing would i replace the injectors to correct the problem?

If the passenger side is washed, replace the CPI, if the driver's side is washed, replace the nut kit. If you do replace the CPI, replace the nut kit as a matter of course as they weaken with age... If you have over a 100k on the existing nut kit, replace them while it's open so you don't have to worry about it later.

Blazer,any idea why mine would do it?I don't have the nice Vortec cover though.

You are having hard starting?

If the passenger side is washed, replace the CPI, if the driver's side is washed, replace the nut kit. If you do replace the CPI, replace the nut kit as a matter of course as they weaken with age... If you have over a 100k on the existing nut kit, replace them while it's open so you don't have to worry about it later.

Will that work if i take the vortec cover and look through the sensor hole to see if the passenger side is washed?

Yes, that will work.

You will smell gas too.

You are having hard starting?
Yea as I said when it's cold it fires right.When it's warm sometimes it fires right up,but must of the time it's turns over for 4-6 seconds before it fires.

So when you say "warm", you are talkig about the engine right?

If the passenger side is washed, replace the CPI, if the driver's side is washed, replace the nut kit. If you do replace the CPI, replace the nut kit as a matter of course as they weaken with age... If you have over a 100k on the existing nut kit, replace them while it's open so you don't have to worry about it later.

Do you think the fuel pressure regulator could be causing this problem?

Yes, but you just don't replace it, you replace the whole injector.

So when you say "warm", you are talkig about the engine right?
Yes.

i replaced the regulator and it seems to have resolved the problem

i replaced the regulator and it seems to have resolved the problem

So it was the CPI unit afterall... Glad you found a fix... Hope you replace d the nut kit while you had the plenum open, it will save you from future problems later on.

it seems to have solved the problem thanks for the help

So when you say "warm", you are talkig about the engine right?
Yes.Is this CPI my problem?Do I even have one?

Yes.Is this CPI my problem?Do I even have one?

No, you have CSFI, similar to CPI but sequentially fired (CPI was discontinued in 95)...If you're running rich one of your injector hoses may be bad. (also causes misfires)

No, you have CSFI, similar to CPI but sequentially fired (CPI was discontinued in 95)...If you're running rich one of your injector hoses may be bad. (also causes misfires)
I just checked the codes and I'm getting a P1351(Ignition control circuit voltage high and ignition control circuit open).Is that weird there 2 descriptions under one code? :screwy: I am also getting a PO420 code(Catalyst system efficiency below threshold,bank 1).Would this fall under your injector hose threoy?What's involved in changing them?

I just checked the codes and I'm getting a P1351(Ignition control circuit voltage high and ignition control circuit open).Is that weird there 2 descriptions under one code? :screwy: I am also getting a PO420 code(Catalyst system efficiency below threshold,bank 1).Would this fall under your injector hose threoy?What's involved in changing them?

Ok, the P0420 code seems to point out that you cat is screwed or the O2 sensor behind the cat is bad. More than likely the cat is plugged.

More info here:

http://www.obd-codes.com/trouble_codes/generic/p0420-catalyst-efficiency-below-threshold-bank-1.php

The other two codes will point to a bad ignition switch.

Ok, the P0420 code seems to point out that you cat is screwed or the O2 sensor behind the cat is bad. More than likely the cat is plugged.

More info here:

http://www.obd-codes.com/trouble_codes/generic/p0420-catalyst-efficiency-below-threshold-bank-1.php

The other two codes will point to a bad ignition switch.
I think somebody hollowed my cat out because it has a hollow sound to it when it's running(before I bought it).I know this because I poked out the wife's cavalier cat and it has the same hollow sound and also threw the PO420 code.The O2 sensor is new.Now this ignition switch.Would that cause the hard starting issue?Why would it fire right up when it's cold,but not whens it's warmed up?Is it the injection issue that this other guy is talking about?This truck is a constant pain in my ass! :banghead:

Could be that.

Also, check your fuel pressure.