Been around for a while. I had a miss which ended up being a bad cap and prompted new plugs and efforts to resolve this issue.
It happens at light to moderate throttle, but not during moderate acceleration. It can happen under light accel.
It's almost as if the truck looses all fire for just a moment.
Cap, rotor, wires, all good.
I swapped out my ign module and coil with another set I had about 6mo ago because it died and wouldn't refire. It had been coughing some then too. I do not remember it having this condition, but it could have.
I've swapped the MAF, cleaned, etc. I also tore the TB apart to clean the IAC. Everything is clean and polished. No sticking.
It runs better. Still hiccups. It is more pronounced at times and at other times it is barely there.
Fuel pressrue is solid with no drop on key off.
MAP was replaced too. No change.
I only have a code scanner for OBD II stuff and it only captures frames if there is an issue. I've got plenty of stuff for OBD I, but haven't spent the $$$$ on the other software.
Help me out guys....or gals...aliens.....muppets...Just no politicians or lawyers. I'm having enough trouble as it is.
intermittent hiccump
Moderator: F9K9
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killian96ss
- Crew K Elite
- Posts: 2669
- Joined: Tue Sep 09, 2003 11:53 am
- Location: Sacramento, California
Re: intermittent hiccump
Mileage? What plugs are you running? What is your fuel pressure? You may have codes stored without any warning lights. Check for codes first and go from therefore.
Steve
Steve
Re: intermittent hiccump
Fixed. Sorry I didn't respond earlier. Life ya know.
I ended up not doing more diagnostic. FP was solid 60 and did not leakdown in 5 min after shutdown. Good platinum plugs I've used before on these trucks (I've had 4 - still got 2). The limited frame data my scanner gives me showed bank 1 rich because it was pulling fuel in the short-term trim.
What did I do....? Threw the kitchen sink at it.
From the jimmy parts bin (totalled and parted):
Swapped distributor. With the two side-by-side I couldn't find the smallest difference in vertical play and neither had distributor gear slop. Put the one from the Jimmy in anyway.
Swapped O2s. The ones in the Blazer had the passenger-side looking normal and the driver's-side looking lean. Go figure.
Swapped spiders. Cleaned up the one from the Jimmy (had been done before) and put in a new FPR. Of note - intake ports for 3 and 5 looked washed as did the land adjacent to them. The FPR appeared caked as the rest of the interior. could have been leaking out the vacuum port, but it did not look like it. If it was, it must have only been doing it at max vacuum (cruise) which is where the trouble was.
Removed the PCM, cleaned contacts and all that.
Cleaned every ground connection under the hood. Added another ground strap from the block to the chassis.
Removed the alternator, cleaned it up, and the connections to it.
Removed all remants of the Vacuum actuator setup. Homemade Posi-lock was installed, but currently disconnected.
Cleaned crank position sensor. I know it works or doesn't, but it was caked with stuff and I cleaned the connectors up while i was at it.
Lots of little cleaning stuff done and reseating connectors.
Cleaned up and put the starter from the Jimmy on so I could also clean/check those connections. Started bad. Put the Blazer's back on after cleaning. Had the kicker wire for the solenoid break off on me so I redid that connection while in there. Appears to have been cracked for some time.
It started right up and runs better than it ever has. I'll be checking mileage. It's at 192,000mi right now. the long-block from the Jimmy is on the stand and is undergoing teardown for a planned rebuild. Mild porting, small cam, balance, and not expecting to set the world on fire. More power down low and hopefully more mileage.
My approah leaves me without knowing the RC, but I got tired of trying to find it. The spider was nasty dirty. Some poppets could have been sticking under nominal load fuel pressure and not when I was on the throttle enough to boost the pressure. The regulator might have been leaking or might have not been providing constant fuel under lower fuel pressures. It worked fine at idle and anything over 1/4 throttle. Perhaps the distributor pickup was going bad or even the CPS was having an issue with its signal. the charging system could have been weak and under lighter load some of the engine management functions would drop below spec. When it would hesitate the lights would dim, but the voltmeter didn't seem to indicate an issue. I chalked it up to the rpm drop when the engine did its thing. I'm good without knowing the specific cause or causes. It runs and all the stuff I did was ultimately good for the truck. Took a long time though.
I ended up not doing more diagnostic. FP was solid 60 and did not leakdown in 5 min after shutdown. Good platinum plugs I've used before on these trucks (I've had 4 - still got 2). The limited frame data my scanner gives me showed bank 1 rich because it was pulling fuel in the short-term trim.
What did I do....? Threw the kitchen sink at it.
From the jimmy parts bin (totalled and parted):
Swapped distributor. With the two side-by-side I couldn't find the smallest difference in vertical play and neither had distributor gear slop. Put the one from the Jimmy in anyway.
Swapped O2s. The ones in the Blazer had the passenger-side looking normal and the driver's-side looking lean. Go figure.
Swapped spiders. Cleaned up the one from the Jimmy (had been done before) and put in a new FPR. Of note - intake ports for 3 and 5 looked washed as did the land adjacent to them. The FPR appeared caked as the rest of the interior. could have been leaking out the vacuum port, but it did not look like it. If it was, it must have only been doing it at max vacuum (cruise) which is where the trouble was.
Removed the PCM, cleaned contacts and all that.
Cleaned every ground connection under the hood. Added another ground strap from the block to the chassis.
Removed the alternator, cleaned it up, and the connections to it.
Removed all remants of the Vacuum actuator setup. Homemade Posi-lock was installed, but currently disconnected.
Cleaned crank position sensor. I know it works or doesn't, but it was caked with stuff and I cleaned the connectors up while i was at it.
Lots of little cleaning stuff done and reseating connectors.
Cleaned up and put the starter from the Jimmy on so I could also clean/check those connections. Started bad. Put the Blazer's back on after cleaning. Had the kicker wire for the solenoid break off on me so I redid that connection while in there. Appears to have been cracked for some time.
It started right up and runs better than it ever has. I'll be checking mileage. It's at 192,000mi right now. the long-block from the Jimmy is on the stand and is undergoing teardown for a planned rebuild. Mild porting, small cam, balance, and not expecting to set the world on fire. More power down low and hopefully more mileage.
My approah leaves me without knowing the RC, but I got tired of trying to find it. The spider was nasty dirty. Some poppets could have been sticking under nominal load fuel pressure and not when I was on the throttle enough to boost the pressure. The regulator might have been leaking or might have not been providing constant fuel under lower fuel pressures. It worked fine at idle and anything over 1/4 throttle. Perhaps the distributor pickup was going bad or even the CPS was having an issue with its signal. the charging system could have been weak and under lighter load some of the engine management functions would drop below spec. When it would hesitate the lights would dim, but the voltmeter didn't seem to indicate an issue. I chalked it up to the rpm drop when the engine did its thing. I'm good without knowing the specific cause or causes. It runs and all the stuff I did was ultimately good for the truck. Took a long time though.