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crazy 340

crazy 340

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I have a 1995 sierra with a 5.7 liter (tbi)
this damn truck drink more than I do:drinkers:
400 km for 110$ or if you prefer 78 liter of gas
tune up made a month ago
plug
cap
rotor
fuel filter
tbi was clean
injector cleanor put in tank
the wire are about 2 years old (a/c delco)
coil was change at the same time

it doesnt pull as hard as it did
take more gas
alwais miss when I step on it even at high way speed you can fill it miss
at 105 km/h fill push a little more its worst a little more seem to desapear and if push it to get the kick down it miss
pull hard few second miss few second pull again miss
I disconnect the egr valve from the egr selenoid,plug the selenoid vaccum port didnt made a change except the light came come:banghead:

:mumum:

I need that fu.... truck to go well

thanks in advance

ps.the o2 sensor are still there
shorty headers
3'' exhaust with Y pipe like OE was
13 pounds fuel pressure at the tbi
 
First thing I would do is pull that cap off and check for cracks. I have seen lots of them cracked out of the box. Also make sure it it tight. That back screw is a #$#%%# and lots of times they get stripped. Pull the plugs and make sure they are not cracked. Know anyone with a OBD II scan tool that can view the live data stream. It will help to isolate the missing cylinder(s).
~Michael
 
Hopefully you gaped the plugs and didn't install right out of the box.:coffee2:

Could also be plug wires if they are two years old. I change mine every year.:coffee2:
 
Getting harder to start?

If it is, I bet the fuel injection spider under/inside the intake manifold is going bad. It's one of the most common problems that plague the fuel injected 4.3/5.0/5.7 engines.

If it's not getting hard to start, I'd say the EGR has a huge chunk of carbon stuck in it and it's hanging wide open 100% of the time, another problem chevy's are infamous for.
 
74Dusted said:
Getting harder to start?

If it is, I bet the fuel injection spider under/inside the intake manifold is going bad. It's one of the most common problems that plague the fuel injected 4.3/5.0/5.7 engines.

If it's not getting hard to start, I'd say the EGR has a huge chunk of carbon stuck in it and it's hanging wide open 100% of the time, another problem chevy's are infamous for.
Click to expand...

Being a 1995 it still has the old throttle body injection setup.

I have a feeling that the catalytic convertor has failed and is a huge restriction in the exhaust system. This would definetly cause bad fuel economy and a loss in power, and could also cause misfiring when under load.
 
check for vacum leak's ...sounds like the vehicle is trying to compensate for false air.... always check basics basics basics..and also all of the above are good things to check..+1 on plugged exhaust it happens more often then people think..
 
check for vacum leak's ...sounds like the vehicle is trying to compensate for false air.... always check basics basics basics..and also all of the above are good things to check..+1 on plugged exhaust it happens more often then people think..
 
BadAss71 said:
Being a 1995 it still has the old throttle body injection setup.

I have a feeling that the catalytic convertor has failed and is a huge restriction in the exhaust system. This would definetly cause bad fuel economy and a loss in power, and could also cause misfiring when under load.
Click to expand...

it could be the catalytic converter if it hade one
Id remove it 3 years ago on the side of the highway
was going to (sanair) http://www.sanairracing.net/champ_dragvendredi.htm
with the duster on the treiller it began to miss,ping
we took a quick look at it and the converter was red hot so we cut the pipe and made the 3 hours left trip un plugged

doesnt seem to have vacuum leak I also check that with brake cleaner the engine didnt made a change

for the egr valve I disconnect it 2 days ago after making it was close
I plugged the egr selenoid to be sure it didnt have vaccum leak
 
Take it to a place with a analizer and have em plug it in and they should be able to tell ya what it is. Some dont charge for this service. The cousin took her o2 diesel in. No charge. Good luck with it.
Small Block
 
First of all, is the check engine light on? That is the first thing I need to know. Unfortunately, you have OBD I and that will leave no data stream and it is hard to set hard codes. Check fuel pressure, check spark on each cylinder to start. This vehicle needs 59 pounds of pressure to start, but will run on less. It just won't run well.
 
Well the miss could be in the wires or ... if it was not doing it b4 the tune up then recheck things .. As for it drinking so much gas get used to it .. my 90 chevy is the same way hahah btw i only looked at the 1st post ..
 
Holy crap,...I'm guessing ya'll got a lot of broke dick chivy's out there,......Start with the simple and cheap (relatively),..Look at the O2 sensor(s) with a scan tool,...replacing them at 100k has helped a lot of Chev's and Chrysler's
 
crazy 340 said:
for the egr valve I disconnect it 2 days ago after making it was close
I plugged the egr selenoid to be sure it didnt have vaccum leak
Click to expand...

One thing I've learned working on chevy's (fords, chevys and imports keep me in business) is that the egr valve is a piece of crap on the 90's - present chevy's.

unplugging it won't do anything if it's at fault, you actually have to physically unbolt it and look inside it to see if its jammed open. (did you check it that way? if so, disregard what i'm saying then)

The 4.3's in particular are infamous for that (but it happens on all chevys), the EGR will jam open when a piece of carbon gets caught in it, it's one of the first things I check when a S10 comes in that isn't running right.

If it is loaded with carbon, some good carb cleaner and a blast with the air nozzle cleans em out. Follow up by dumping the following down the throttle body (while running)

Mixture of Baking Soda, Water and a little bit of kerosene & atf. bring the rpms up above 1,500 and start dumping it in slowly, do not let it stall. Once your done, let it continue to run for a few minutes (5 - 10 minutes) Do this outside! preferably with the exhaust aimed toward your 'favorite' neighbor (favorite being the guy you hate the most) This thing will turn a 100 yard radius into Zero Visibility 'cant see your nose' type fog! But your combustion chambers, pistons, intake, valves, etc will be Spotless and so shiny you can eat off them.
 
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