# 92-93 4cyl bogging at about 2800-3000rpm



## tahoe (Jan 11, 2012)

This thing is not throwing any codes, I have had it for 15yrs it has 240K and has been great. Recently last 6mo it started to intermittently bog down but it would kinda clear up and go away. Now if you need to get into the pedal to go up a hill or go faster it just sounds kinda like it shuts off even though it is still running, if you let up on the pedal it kinda jerks and runs normal just can't give it more or it just bogs down.
I changed the plugs ,wires,cap,rotor,coil and checked the timing, the cat wasn't really blocked but I pulled it to see if it helped, no help. I also sprayed sensor cleaner down the little hole on the side of the throttle body base to clean the little wires in there ( maf ) ? and they look intact, I also checked the wiring and ohmed out the air temp sensor on the air cleaner base it seems ok. I'm lost at this point.
Scot


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## smj999smj (Jan 1, 2006)

I would check for vacuum leaks, especially at the intake gasket and throttle chamber gaskets, using some carb cleaner. I would also confirm the fuel pressure is within spec and test the throttle position sensor. When you checked the ignition timing, did it need to be adjusted? If it was off approx. 8 degrees (retarded), it's possible that the timing chain jumped a tooth.


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## tahoe (Jan 11, 2012)

Timing was ok, changed the fuel filter but I did not check the pressure as it seems really difficult, it was hard enough getting the fuel line off of the filter, are you supposed to sub in another piece of tubing at the filter area with a gauge ? I do not know the test procedure for the tps. I will try carb cleaner around the gaskets but they look real good, of course that doesn't mean there good.
Thanx


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## smj999smj (Jan 1, 2006)

Fuel pump testing and inspection procedure:


Turn the key on and listen for fuel pump noise for 5 seconds.

If sound is heard, proceed to step 2.
If sound is not heard, perform fuel pump test. If fuel pump is O.K., proceed to Computers and Control Systems and check the fuel pump control circuit.

Fuel Pump Fuse



Remove the fuel pump fuse from the fuse box (located under the L.H. side of the dash).
Start the engine and run until the engine stops.
Turn the key off and reinstall the fuse. Fuel pressure is now released.
Disconnect the fuel inlet hose at the throttle chamber.
Install a high-pressure fuel gauge (0 to 60 psi) between the hose and throttle chamber with a "T"-fitting.
Start the engine and check for leakage at the fittings.
Allow the engine to idle and observe the gauge reading.

If fuel pressure is 33.3 psi (226 kPa, 2.30 kg/cm2), fuel pressure is O.K.. END TEST.
If fuel pressure is below 33.3 psi (226 kPa, 2.30 kg/cm2), proceed to step 9.
If fuel pressure is above 33.3 psi (226 kPa, 2.30 kg/cm2), proceed to step 15.

Disconnect the fuel pressure regulator vacuum hose and check for vacuum at the fuel pressure regulator hose.

If vacuum does exist, proceed to step 10.
If vacuum does not exist, inspect the throttle chamber for restriction and clean and replace as needed.

Observe the gauge readings.

If fuel pressure does not raise to 43 psi (294 kPa, 2.94 kg/cm2) after removing vacuum hose, replace the fuel pressure regulator and re-test.
If the fuel pressure does raise, inspect the fuel filter for restriction, if O.K. proceed to 11.

Remove the fuel cap and retest.

If O.K., replace the fuel cap and re-test.
If no change occurs, proceed to step 12.

Remove the fuel pump and inspect the pick-up screen for restriction.

If O.K. proceed to step 13.
If not O.K., clean the screen and re-test.

Inspect the fuel delivery lines for restrictions (kinks, bends or collapsed hoses).

If O.K. proceed to step 14.
If not O.K., repair or replace as needed and re-test.

Replace the fuel pump and re-test.
Disconnect the fuel pressure regulator vacuum hose and check for vacuum at the fuel pressure regulator hose.

If vacuum does exist, proceed to step 16.
If vacuum does not exist, inspect the throttle chamber for restriction and clean and replace as needed.

Observe gauge readings.

If fuel pressure does not raise after removing vacuum hose, replace the fuel pressure regulator and re-test.
If the fuel pressure does raise, proceed to step 17.

Inspect the fuel return lines for restrictions (kinks, bends or collapsed hoses).

If O.K. proceed to step 18.
If not O.K., repair or replace as needed and re-test.

Replace the fuel pump and re-test.


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## smj999smj (Jan 1, 2006)

TPS component inspection:

Disconnect throttle sensor connector.
Using an ohm meter, check resistance across terminals e and f. Resistance value should change smoothly, without any glitches, from approximately 1 to approximately 9 ohms as the throttle is moved from idle to WOT.

Replace sensor if it fails the above test.

Another thing you should try: wiggle the engine electrical harness at the bend where it goes from the firewall to the side of the engine head. If wiggling the harness with the engine running changes anything, you may have a poor electrical contact due to a poor splice connection. There is a common ground for the throttle sensor, exhaust gas sensor and engine coolant sensor. It is a single wire that routes back to the ECM that splices to three wires at a metal crimp splice. All of the wires are black with a green stripe. You'll need to open up the harness to find the splice and solder the splice connection. This issue was most common on 94-94 KA24E Hardbodies, but could affect earlier years with the KA24E engine.


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## tahoe (Jan 11, 2012)

Wow ! Thanx smj999smj ! Looks like I have some work to do. Will update.
Scot


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## tahoe (Jan 11, 2012)

Well, 35 idle, 45 vacuum disconnected, goes from 35 to almost 40 when I gas it. It will rev all the way up to like 5k just sitting there it is only under load that it happens, could the fuel sock still be plugged ? Also the TPS tested ok. What are the OHMS for the MAF ? Seems odd the line goes into the fuel rail then the pressure regulator is on the line going back to the tank, never been touched so must be right, just figured the fuel would be regulated on the way in, goes it just keeps the charge on the rail constant.


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## GeoBMX4Life (Mar 25, 2010)

My truck was REAL intermittant...turned out to be the MAF...physically pull the MAF off and check the wires...mine would be fine...then crap out...the tiny wires would connect and dissconnect...and that was the pblm...pain in the butt..smj999smj`s suggestion is the best if this doesn`t work!!!


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## tahoe (Jan 11, 2012)

: ( Well did all the above plus changed the distributor for a new one, no change, thing runs really good till right at about 2800, then it just bogs down like the ignition is off kinda. It has no stumbling at idle decent power up to the magic #, the plugs were kinda black around the ring of the base, not on the ground prong or electrode though, no way to get it to go over 2800 unless it is out of gear. Wondering if the computer is just storing limp mode now ? Is that something that happens ? If so is there a special procedure other than a long ( several hours ) battery disconnect ?

Trying to hook my son up with a good little starter truck at 17, but were both getting kinda flustered.

Scot + Nick


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## tahoe (Jan 11, 2012)

Messed with it a bunch more today, went through the computer diagnostic stuff no codes but did the reset any way, this brought no change. Did some more road testing and found it odd. If I barely push the gas pedal while accelerating I can get it to go up to around 4k rpms and on and on through each gear, if it just starts to bog I can just ease up on the pedal then start to just gradually give it more pedal and move through the bog down and get up to about 4k. Another odd way to test is in neutral, if I gradually push the pedal I can get it up to around 5k or so, but if I floor it, it will go to around 4k then drop fast to 2k then back up to 4k and it will just keep doing that,like the spark or fuel is being cut and then turned right back on.

Please help, some one has had to have this issue and then figured out how to make it go away.

Scot


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## rogoman (Dec 16, 2004)

Sounds like it could be a MAF failure problem. Check the MAF harness connector pins for any oxidation.

Also check the intake system vacuum with a vacuum gauge. At idle, the reading should be 18 - 20 InHg. At 3,000 RPM, it should be around 21 InHg.


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## tahoe (Jan 11, 2012)

Thanx for your response rogoman. Is there a certain gauge to use for this and where would it be hooked into. I fix appliances so I have used a water column gauge for checking gas pressure and have one but it only goes up to 15" as you should never have that kind of gas pressure, never used it for anything but that, I do know how that style works, is this something I get at napa auto pts ?


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## smj999smj (Jan 1, 2006)

Napa sells a couple times. Go to their website and look up vacuum & pressure tester #BK 7001715. It runs about $22. Sears also sells them in their automotive tools dept. You can also find them online.

http://napaonline.com/Catalog/Resul...iagnostic+Tools_Related+Products|vacuum&Nty=1


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## tahoe (Jan 11, 2012)

Thank you I will check that out next:woowoo:


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## j420somewere92 (Mar 12, 2021)

Please tell me you figured out this problem. Mine is a 93 Hardbody 4cyl with manual trans and it's doing the same thing just with the added problem of if I leave it idling to long it'll die and won't start again for at least 5-10 minutes unless I pop the clutch.


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## smj999smj (Jan 1, 2006)

j420somewere92 said:


> Please tell me you figured out this problem. Mine is a 93 Hardbody 4cyl with manual trans and it's doing the same thing just with the added problem of if I leave it idling to long it'll die and won't start again for at least 5-10 minutes unless I pop the clutch.


Member "Tahoe" hasn't been seen in 9-years. Sometimes you're better off starting a new topic rather than tagging onto one that's years old to better address the issues with your specific truck. Make sure to include year, model, engine and trans (like you did), your problem and any specific work or parts replaced to address the issue. Welcome to the forums!


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