hello ive got a 95 blazer vin w obd2
its stumbles for a few seconds after a stop at light acceleration. when rpms get to about 2000rpm it sounds like it boggs down a bit just for a few seconds then picks back up. only when warm. also if I hit the gas a bit harder it wont do it. it does have a slight miss at idle.


no codes
only for evap no purge detected - found the problem today the solenoid is not working. 12v to solenoid and nothing.
and the rear o2 sensor after cat heater circuit


what ive replaced
pump
injectors
fuel filter
air filter
spark plugs
wires
cap n rotor
tps
egr cleaned
vacuum lines new
whole upper plenum spotless
fuel 60psi


so what ive found out is that the dizzy has a bit of slop in it. so im wondering if that could be it
heres a video


https://www.youtube.com/watch?v=0tsD...ature=youtu.be

 

Your 1995 is equipped with Central Multiport Fuel Injection, (CMFI) using OBD1.5 computer controls, (Not OBDII). It requires a scan tool with the proper software to communicate with your PCM. Not all scan tools will communicate with it.

"no codes
only for evap no purge detected - found the problem today the solenoid is not working. 12v to solenoid and nothing.
and the rear o2 sensor after cat heater circuit"

What DTC's were retrieved, and in what order? The purge solenoid is supplied battery voltage with the ignition in the RUN position. The PCM applies ground to activate the solenoid.

At this point, don't worry about the downstream oxygen sensor, it has no effect on engine performance.

As for the distributor: The movement in the video is normal. End play, (up and down) is fine. When the engine is running, the teeth are cut to pull the shaft down. Rotational play increases as the teeth wear, not an issue in the video. The important thing is side to side play of the shaft, there should be no perceivable movement in any direction.

I would suggest checking regulated fuel pressure and leakdown at the service port near the distributor, and fuel pump maximum output pressure and leakdown at the fuel filter outlet. The following link explains how to do the tests. The article is based on CSFI, which has different pressure specs, but the procedures are the same. Post all 4 of your readings so we can analyze them. At the end of the article there is a list of necessary parts to build the adapter for the fuel filter. You will need to use the "1996 and older" list. https://blazerforum.com/forum/2nd-ge...eakdown-88305/

 

thank you for helping me out.
and I know for a fact my fuel pressure is good. but the leek down test fails
it depressurizes pretty fast ever since I replaced the pump and injector assembly. it has always done that. key on it pressurizes good then it starts to go down rapidly. it has always started and ran perfect. until a few months after replacing those. actually it has done it ever since I replaced the upstream o2 sensor I think is when I started noticing it. have to fine a pressure gauge again to test for the 10th time.

 

Following the instructions in the link will tell you where the problem is, (tank or plenum). Fuel pressure and leakdown are critical on these engines, if they're out of spec, there will be driveability issues with it.

 

well I got a pressure gauge and key on is 58psi. drops to around 50 after five minutes. running is around 54psi. snap throttle and jumps up about 5psi.


I got a cheap Chinese gauge so if I tilt the gauge psi increases about 3psi. not sure why its doing that. so it could be at 57psi running or 61psi key on.


also I have engine oil in my vacuum lines. not trans fluid. the main vac line on passenger side rear plenum was really weak and oil soaked. and it got in my hvac lines. just a few drops it looks like but I replaced the lines and a few weeks later the new main vac line is already starting to get soft again. I changed the pcv valve and hoses to it.


could I just run two breathers on the valve covers and cap the pcv line to stop that?

 

You need an accurate fuel pressure tester. Check fuel pressure and leakdown at the fuel filter outlet and then at the service port near the distributor. See the link in post #2. Post all 4 readings. GM does not publish any "engine running" fuel pressure specs for this engine, they are totally worthless. All readings must be taken with the engine off.


The hoses for the PCV system need to be oil rated or they will deteriorate. The PCV valve is a calibrated vacuum leak and must be present. If you cap off the PCV feed, the PCM will be unable to control fuel mixture correctly.

 

I borrowed a buddys snap on gauge. heres the readings
service port 60psi
leak down 50psi after 10min


at fuel filter 94psi
leak down 71psi after 10min


surprising the leak down test did fail this time. when I first changed the pump it wouldn't hold pressure. must needed some time to seat in.


also the vac line that has the oil in it is the main line that feeds the vac ball. not the pcv line. why would that line be oil soaked and getting engine oil into my hvac lines aswell?

 

These readings are too low.
Shows as ok as it stays above 55psi. Does it continue to leak down over 10 minutes? Or does it stabilize?

Your vacuum switch on the transfer case is leaking fluid from the t-case into the vac system. You will also very likely find that your t-case is over full. If you pull the fill plug on the back (higher of the two) and fluid pours out, then the input seal on the front of the t-case is bad and needs to be changed. That requires dropping the t-case.

 

this is the cpi motor. it says 50psi is fine at the service port after ten min. right?
it seems to continue to drop past the ten min aswell.


and its engine oil in the vac lines. not trans fluid. I replaced the vac switch last summer and checked the tcase and its not overfilled.


I had the trans rebuilt and theres nice pink red fluid in it. I have installed a clear line to the hvac hose to see what color it is and its brown. the oil is for sure coming from the pass rear intake plenum hose that leads to the vac ball. the line is starting to get soft again after just 2 weeks of replacing that line. I pulled the 4x4 hose and its dry no trans fluid and since its up higher than the hvac and vac ball line it doesn't have any engine oil in it.

 

so anybody know why engine oil is getting in my vac lines?


also I bought a obd link sx cable and scan xl pro with the gm enhanced diagnostics. and I cant get it to read cam retard (cmp). the program says cmp is at zero degrees all the time. tried it on a 97 bravada and its at zero aswell after replacing intake manifold gaskets. seems kind of odd that its not out at least one degree.