2003 chevy venture p0304

[Trievel]

so i bought this van the other day,thinking this would be an easy fix, codes p0304 & p0132 ...wrong!!! replaced all plugs/wires and the o2 sensor bank 1 sensor 1. still misses. check coil,coil is good,have great spark. oil is clean,no milk. do a compression test,(only on front side so far,started pouring rain). all 3 cylinders exact same psi,around 100psi. is this bad? am i looking at a head gasket,or intake manifold gasket issue to fix this code?

any input GREATLY appreciated,as i have no job currently,and need to be able to get the kids around,sold my VW Beetle to buy this. and it's gotta get fixed ASAP as i start a job on the 22nd... Please help!!!

 

[DIC]

 

[Seanbev24]

Time to load an injector into the parts cannon? But seriously, do you have access to a scan tool that shows live and freeze frame data?

 

[MattT]

Time to load an injector into the parts cannon?

That's the next "logical" step. Makes a heck of a lot more sense than replacing an O2 sensor

Or if money is tight just switch a couple injectors and see if that moves the code.

 

[Drew_flux]

so i bought this van the other day,thinking this would be an easy fix, codes p0304 & p0132 ...wrong!!! replaced all plugs/wires and the o2 sensor bank 1 sensor 1. still misses. check coil,coil is good,have great spark. oil is clean,no milk. do a compression test,(only on front side so far,started pouring rain). all 3 cylinders exact same psi,around 100psi. is this bad? am i looking at a head gasket,or intake manifold gasket issue to fix this code?

any input GREATLY appreciated,as i have no job currently,and need to be able to get the kids around,sold my VW Beetle to buy this. and it's gotta get fixed ASAP as i start a job on the 22nd... Please help!!!

100 psi sounds low too me, I would want 150+ psi in the cylinder. give the comp test another go when it stops raining. make sure you have a full battery, also do a wet comp test.

 

[snyder]

100 psi sounds low too me, I would want 150+ psi in the cylinder. give the comp test another go when it stops raining. make sure you have a full battery, also do a wet comp test.

Make sure you block the throttle blade open during comp test also.

 

[Lotek]

Compression seems a bit low, but even, possibly a weak battery, probably not a concern, I would check the resistance of the injectors cold, unplug and check at the c102 connector that comes out from under the manifold so you don't have to pull the upper intake. you are looking for 11-14 ohm between the pink wire and the black, lt green/blk, pink/blk, lt blue/blk, blk/white, and yellow/blk. #4 is lt blue/blk, the pink is the power feed to all the injectors. C102 is a 16 pin connector sitting on top of the motor. On a cold motor with a good ohm meter, even a couple of ohms out of spec is bad.

 

[Drew_flux]

Make sure you block the throttle blade open during comp test also.

good catch there^^ forgot to post this.

 

[Trievel]

That's the next "logical" step. Makes a heck of a lot more sense than replacing an O2 sensor

Or if money is tight just switch a couple injectors and see if that moves the code.

the o2 sensor was bad,as per the p0132 code,which went away after replacing said o2 sensor. only problem with switching injectors around is i have to remove the upper intake manifold to do so. which of course,means replacing that gasket set everytime the UIM comes off...

 

[Trievel]

Compression seems a bit low, but even, possibly a weak battery, probably not a concern, I would check the resistance of the injectors cold, unplug and check at the c102 connector that comes out from under the manifold so you don't have to pull the upper intake. you are looking for 11-14 ohm between the pink wire and the black, lt green/blk, pink/blk, lt blue/blk, blk/white, and yellow/blk. #4 is lt blue/blk, the pink is the power feed to all the injectors. C102 is a 16 pin connector sitting on top of the motor. On a cold motor with a good ohm meter, even a couple of ohms out of spec is bad.

battery is brand new,put it in yesteday. i dont have a ohm meter anymore,my ex stole it,haha. i'll try and borrow one from the parts store.

 

[Trievel]

100 psi sounds low too me, I would want 150+ psi in the cylinder. give the comp test another go when it stops raining. make sure you have a full battery, also do a wet comp test.

i kinda did a quickie compression test with the reading last night,because of the weather. i simply took a plug out & hooked up the compression gauge,and started then van,let it run for 15 secs. repeated on all 3 front cyls. just looking for a major drop in CR from one cyl to the next. would that really affect the compression reading? would it show high or low compression compared to the normal way of testing? and go figure,today,its windy as al hell,and snowing...l

 

[Copytech]

I wouldn't completely rule out the coil just yet. I have seen them check good until a load (as in compression) is applied.
I have a a Subaru that would only misfire while going uphill but would run fine any other time. Replaced the coil and the problem went away.

If it has a coil pack, the kind that fires multiple cylinders at the same time, say three coils but 6 cylinders. Try swapping wires on the coil to see if the misfires changes cylinders.

 

[Trievel]

I wouldn't completely rule out the coil just yet. I have seen them check good until a load (as in compression) is applied.
I have a a Subaru that would only misfire while going uphill but would run fine any other time. Replaced the coil and the problem went away.

If it has a coil pack, the kind that fires multiple cylinders at the same time, say three coils but 6 cylinders. Try swapping wires on the coil to see if the misfires changes cylinders.

it runs 3 coils, 2 cyls per coil. i pulled the #4 wire off the plug with the engine running,laid against valve cover,and there is plenty of spark

 

[kornjulio]

I have a 2000 Venture & had the same lean code & poor driveability. Wound up being the middle injector for the rear bank....would've liked to change them all, but too expensive.

 

[Trievel]

I have a 2000 Venture & had the same lean code & poor driveability. Wound up being the middle injector for the rear bank....would've liked to change them all, but too expensive.

did you have a cyl. misfire code too? p0304,is cyl 4, which is the middle injector,on the front side..so,you would have had a p0303?

 

[Trievel]

to be clear,this is the compression readig just pulling 1 plug at a time,and NOT revving,or "snapping" the throttle,simply idling...

100psi on all 3 front cyls

 

[kornjulio]

to be clear,this is the compression readig just pulling 1 plug at a time,and NOT revving,or "snapping" the throttle,simply idling...

100psi on all 3 front cyls

You're doing it wrong. Don't start the engine. Throttle plate wide open, then crank it a few times. Note the reading.

 

[bgott]

That is good pressure for a running compression test. If it had been low one one cylinder running you would have a weak/broken valve spring or other valve problem. To do an accurate running test, however, you'd want to pull the schrader valve out of the tester hose so you could see if the pulses were even. Pull the fuel pump relay so it won't start and try it again. Then swap the rear injectors to the front, if you have a dead one it'll be easier to change it.

 

[rtremaine]

I would do:

check for vacuum leak (intake manifold gasket failure, etc)
verify injector signal (pulse)
clean injector(s)
replace injector

 

[Copytech]

it runs 3 coils, 2 cyls per coil. i pulled the #4 wire off the plug with the engine running,laid against valve cover,and there is plenty of spark

You should still swap the plug wires on the coil to see if the misfire changes cylinders.
Believe it or not, just because you checked the spark in the open air does not mean it is firing under compression.

 

[NHBandit]

These engines as well as their sister 3.1 engines are known for having intake gasket problems. It's extremely common. What did the plugs look like that you removed ? When I was working for a used car dealership I probably replaced 50 of them in a 4 year period. As stated a compression test to be accurate should be done with the throttle butterfly open, ALL plugs removed, and not running.

 

[Gus68]

I'm just trying to remember off of the top of my head, but isnt a P0304 a missfire on cylinder number 4? If so, why are you compression testing the front three cylinders? If memory serves me right, I thought number 4 was the second one on the back side of the engine. I would ohm the injector like Lotek said, or if worse comes to worse swap # 4 injector with either one from another cylender and see if the miss follows that injector, or replace with a new one. Usually you will not ruin the upper intake gaskets, if you do, a new set is fairly cheap, and if you have to remove the upper intake again, the new gaskets wont tear.

 

[1949 caddyman]

The front cylinders are 2,4&6. The rear are 1,3&5. If it was compression problem It would have shown up on running compression test. But compression should be checked cranking engine. It could be a stuck closed injector. Try tapping the body of #4 injector with a large screw driver with the engine running. If you can free it up then add Chevron Techron cleaner. A few years ago we would see this problem daily. I am a retired Chevrolet tech.

 

[Silent One]

Use a stethoscope and check to see if the injector sounds like it is working adequately. I have a 2002 Olds Silhouette counterpart and have to run an injection cleaner through the rail once a year to keep the misfires at bay. And yes, I always use a Tier 1 brand gasoline.

 

[Trievel]

These engines as well as their sister 3.1 engines are known for having intake gasket problems. It's extremely common. What did the plugs look like that you removed ? When I was working for a used car dealership I probably replaced 50 of them in a 4 year period. As stated a compression test to be accurate should be done with the throttle butterfly open, ALL plugs removed, and not running.

the plugs looked brand new.(autolite 606) cyl. 4 plug cracked in half as soon as i tried to take it out. and cyl. 3 was already cracked in half just laying in the hole on the back side.

i'm goin to hopefully pull the upper mani tommorow,and check/clean all the the injectors. i'll try swapping the coils too,but i tested the one in question at autozone today,it tested good. :shrug: i'll also put a noid light on the injector pigtail to see if it's even getting a signal. i also sprayed carb cleaner all over both intake manifold gaskets,and throttle body gasket to check for a leak,not a hiccup...

 

[Stick]

Quit messing around and start over with your diagnostics... Have you looked at any actual scan data, or just pulled codes?

I'd also highly suggest that you get over to Free Parking and do some reading.

Can someone walk me through the procedures?
How-to: OBD2 diagnostic strategy
A diagnostic mystery for you to solve. Ford Ranger P0171/P0174...

 

[Trievel]

Quit messing around and start over with your diagnostics... Have you looked at any actual scan data, or just pulled codes?

I'd also highly suggest that you get over to Free Parking and do some reading.

Can someone walk me through the procedures?
How-to: OBD2 diagnostic strategy
A diagnostic mystery for you to solve. Ford Ranger P0171/P0174...

i dont have access to actuall scan data,don't have those tools. and can't afford to take it to a shop. so after reading all that (your 3 links) i'm still not sure what you think i should do? what diagnostics have i done wrong? or not done at all? (i know the running CR test isn't the preffered method,but it will still show if you have a major drop from one cyl. to the next, like a head gasket problem,which is what i was looking for)

 

[kornjulio]

Autolite plugs? I'd put Delco plugs and wires on. No debate. Then see where you're at. But I've got evidence that on high-mileage motors, the injectors do go bad (or clogged). Mine was 140Kish when it happened to me.

 

[wafrederick]

Could be headgaskets,blow out in the center taking in anti freeze in the cylinders.Had a few come with a missfire with the 3400,was blown headgaskets.Last one was a Buick with this same engine,found anti freeze in the front cylinders due to a blown head gasket after removing the front head.The code was a missfire code

 

[Trievel]

Autolite plugs? I'd put Delco plugs and wires on. No debate. Then see where you're at. But I've got evidence that on high-mileage motors, the injectors do go bad (or clogged). Mine was 140Kish when it happened to me.

was autolite when i got it. first thing i did was put in AC factory iridiums,bosch wires

 

[Trievel]

Could be headgaskets,blow out in the center taking in anti freeze in the cylinders.Had a few come with a missfire with the 3400,was blown headgaskets.Last one was a Buick with this same engine,found anti freeze in the front cylinders due to a blown head gasket after removing the front head.The code was a missfire code

could be,thats why i checked for variance in running CR. but all cyls. are within 2-4psi. and i changed the oil as i always do when i buy a new vehicle,and there is no coolant in the oil,and no oil in the coolant. nor does it burn/lose any oil or antifreeze,or leak externally.

 

[wafrederick]

below 100 psi during a compression test is not good called not good enough.100 psi and up is what you want for a compression test.3400s do have problems with blown headgaskets causing a miss.Antifreeze in the cylinders is not good,can destroy a piston.

 

[kornjulio]

OK on the plugs - so you're having the problem with fresh delcos. Assuming you got the wires put back on right (will run reallly bad if you don't - and I know this from experience, too); I'd pull the upper intake like you said & go after the injectors.

You can go two ways here: swap injectors, reassemble, and see if the problem follows the injector; or just replace the suspect injector.

I took the latter route & took a chance with a new injector. There's pros & cons of shotgunning it this way, but if the injector is bad, you've got to tear that sucker down again to replace it when you could've done it the first time. Not a hard job, but wastes time IMHO...

 

[Stick]

i dont have access to actuall scan data,don't have those tools. and can't afford to take it to a shop. so after reading all that (your 3 links) i'm still not sure what you think i should do? what diagnostics have i done wrong? or not done at all? (i know the running CR test isn't the preffered method,but it will still show if you have a major drop from one cyl. to the next, like a head gasket problem,which is what i was looking for)

Seems like if you can't afford to take it to a shop, you probably can't afford to throw parts at it either.

You said you've got spark, but how good is that spark? Is it strong enough to fire a ST-125 style spark tester? It's easy to fire a plug at atmospheric pressure, but is it breaking down under a load?

What kind of fuel trims are you running, short term and long term? Just those numbers can tell you a whole lot about what's going on inside the engine. Is there any way that you can beg or borrow a scan tool that supports live data?

I really hate Ohm checks, but did you do the check on the injectors that Lotek suggested?

You've got compression numbers, which is great. They're running compression numbers, which is ok, but did you do the running compression check properly? If you're doing running compression, you need to have the schrader valve out of the hose and be bleeding off pressure to get accurate numbers. If you're doing a static compression check, the schrader valve needs to be in the hose, the ignition or fuel system needs to be disabled, all the plugs need to be out, and the throttle needs to be wide open.

below 100 psi during a compression test is not good called not good enough.100 psi and up is what you want for a compression test.3400s do have problems with blown headgaskets causing a miss.Antifreeze in the cylinders is not good,can destroy a piston.

100psi is fine for running compression, which is the test he seems to have run. I'm still questioning if he did it properly, but they aren't numbers that should be overly concerning at this point.

 

[Trievel]

i dont know,i dont have an st-125 style spark tester. as far as fuel trims,no clue,i have no access to the required scan/data tools.

Seems like if you can't afford to take it to a shop, you probably can't afford to throw parts at it either.

You said you've got spark, but how good is that spark? Is it strong enough to fire a ST-125 style spark tester? It's easy to fire a plug at atmospheric pressure, but is it breaking down under a load?

What kind of fuel trims are you running, short term and long term? Just those numbers can tell you a whole lot about what's going on inside the engine. Is there any way that you can beg or borrow a scan tool that supports live data?

I really hate Ohm checks, but did you do the check on the injectors that Lotek suggested?

You've got compression numbers, which is great. They're running compression numbers, which is ok, but did you do the running compression check properly? If you're doing running compression, you need to have the schrader valve out of the hose and be bleeding off pressure to get accurate numbers. If you're doing a static compression check, the schrader valve needs to be in the hose, the ignition or fuel system needs to be disabled, all the plugs need to be out, and the throttle needs to be wide open.



100psi is fine for running compression, which is the test he seems to have run. I'm still questioning if he did it properly, but they aren't numbers that should be overly concerning at this point.

 

[znowaczyk]

did you have a cyl. misfire code too? p0304,is cyl 4, which is the middle injector,on the front side..so,you would have had a p0303?

The front cylinders are 2,4&6. The rear are 1,3&5. If it was compression problem It would have shown up on running compression test. But compression should be checked cranking engine. It could be a stuck closed injector. Try tapping the body of #4 injector with a large screw driver with the engine running. If you can free it up then add Chevron Techron cleaner. A few years ago we would see this problem daily. I am a retired Chevrolet tech.

4 is the middle cylinder in the back...

 

[Trievel]

4 is the middle cylinder in the back...

nope...

 

[Trievel]

so,did a running compression test just now,and got 0-5psi cyl 4. 2 & 6 read like this pic....**** me...

 

[B&H]

Looks like that's your static test. Bad news. Pull the front valve cover off, back off the rockers on #4 and air it up!

 

[bgott]

Pull the valve cover. Those engines have been known to break rocker bolts.