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| Throwing Overboost P0234 code as accelerate through about 60 http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=71884 |
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| Author: | pappyrsg [ Thu Oct 04, 2012 7:40 pm ] |
| Post subject: | Throwing Overboost P0234 code as accelerate through about 60 |
Recently purchased 2006 Sport throwing P0234 at moderate accel through about 60mph. Vehicle threw no codes on test drive, but at start of drive home (2000+ miles), first accel on to interstate, started throwing P0234.. over-boost. Doesn't throw ANY codes unless accelerating through that higher speed (can whack the heck out of it at lower speeds with no issue). Doesn't take super hard accel... just anything beyond 90-year-old-lady accel. Works fine if I baby it up to speed (hey, drove 2000mi with highway speeds of 70+ and generally no issue... until I try to accel too hard. Have replaced boost solenoid filter, fixed apparent leak (soot on pipe and exhaust smell) at junction between exhaust pipe to EGR (PA dealer ID'd as 'crack' during smoke test by relatively ignorant tech), 'waste gate' actuator seems to be moving OK, currently running K&N filter but throws same code with stock new filter (original air filter box found full of field mouse nest debris but nothing beyond filter). Hoses 'look' good but at a bit of a loss of how to do true leak test there... intake or exhaust... can I use soapy water as with tire tube or natural gas leak? Could I have dirty turbo vanes... debris? How to clean? Ideas?... next steps? |
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| Author: | MRausch82 [ Thu Oct 04, 2012 8:16 pm ] |
| Post subject: | Re: Throwing Overboost P0234 code as accelerate through abou |
Search "Italian Tune Up" and that may fix it. May need to do it several times. Are you in PA or was it purchased in PA? |
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| Author: | jlgail4309 [ Thu Oct 04, 2012 8:26 pm ] |
| Post subject: | Re: Throwing Overboost P0234 code as accelerate through abou |
http://colorado4wheel.com/manuals/Jeep/KJ/ U should be able to down load the service manual to your computer. It's funny the service manual for over boost and under boost look to be the same. I had the under boost I replaced the BOOST PRESSURE ACTUATOR. Secondary Runner Valve 4606226AC When Monitored: With the ignition on. ² Set Condition: The Boost Pressure Sensor signal voltage is above 4.79 volts for 0.5 seconds. Possible Causes BOOST PRESSURE SENSOR GROUND CIRCUIT SHORTED TO VOLTAGE BOOST PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO VOLTAGE BOOST PRESSURE SENSOR GROUND CIRCUIT OPEN BOOST PRESSURE SENSOR POOR CONNECTOR TERMINAL CONTACT ENGINE CONTROL MODULE (INTERNAL) ENGINE CONTROL MODULE (SENSOR SIGNAL SHORTED TO VOLTAGE) Diagnostic Test 1. CHECKING FOR CURRENT DTC NOTE: If a P0234 or P0299 DTC is present with this DTC, diagnose P0234 or P0299 DTC before continuing. NOTE: If DTC P0641, P0651 or P0697 is present with this DTC, diagnose DTCs P0641, P0651 or P0697 before diagnosing this DTC. NOTE: If the ECM detects and stores a DTC, the ECM also stores the engine/vehicle operating conditions under which the DTC was set. Some of these conditions are displayed on the scan tool at the same time the DTC is displayed. NOTE: Before erasing stored DTCs, record these conditions. Attempting to duplicate these conditions may assist when checking for an active DTC. NOTE: Ensure all turbocharger inlet and outlet tubes are connected properly, without damage and restriction before continuing with this test. Also ensure the wastegate actuator and actuator rod are attached and functioning properly. Turn the ignition on. With the scan tool, erase ECM DTCs. Cycle the ignition key on and off several times, leaving the key on for at least 10 seconds at a time. With the scan tool, read ECM DTCs. Did this DTC set again? Yes >> Go To 2 No >> Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING) ² When Monitored: With the engine running. ² Set Condition: The Boost Pressure Sensor indicates actual turbocharger boost is less than the ECM setpoint. Possible Causes AIR FILTER AIR RESTRICTION AIR LEAKS BOOST CONTROL VACUUM SUPPLY BOOST PRESSURE ACTUATOR TURBOCHARGER Diagnostic Test 1. CHECK FOR ACTIVE DTC NOTE: If the ECM detects and stores a DTC, the ECM also stores the engine/vehicle operating conditions under which the DTC was set. Some of these conditions are displayed on the scan tool at the same time the DTC is displayed. NOTE: Before erasing stored DTCs, record these conditions. Attempting to duplicate these conditions may assist when checking for an active DTC. NOTE: Ensure all turbocharger inlet and outlet tubes are connected properly, without damage and restriction before continuing with this test. NOTE: If DTC P0401 or P0402 is present with this DTC, diagnose P0401 or P0402 before diagnosing this DTC. Turn the ignition on. With the scan tool, erase ECM DTCs. Test drive the vehicle. Monitor the scan tool for ECM DTCs. NOTE: A clogged Boost Pressure Solenoid Air Filter can cause this DTC to set. Inspect this filter and replace as necessary before continuing with this test. Did this DTC set again? Yes >> Go To 2 No >> Test Complete. 2. AIR FILTER Turn the ignition off. Remove and inspect the Air Filter for soiling or excessive dirt and debris which may cause air flow restriction. Were any of these problems found? Yes >> Replace the Air Filter element. Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING). No >> Go To 3 3. AIR RESTRICTION NOTE: Inspect all air intake and turbocharger related tubes for damage, restriction or poor connection. Any of these conditions can cause a this DTC to set. Turn the ignition off. Inspect all air intake, crankcase vent and turbocharger related tubes and connections. Were any problems found? Yes >> Repair or replace as necessary. Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING). No >> Go To 4 4. CHECKING THE BOOST CONTROL VACUUM SUPPLY Refer to symptom Checking The Boost Control Vacuum Supply to check the turbocharger vacuum supply system. Were any problems found? Yes >> Repair as necessary Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING). No >> Go To 5 5. CHECKING FOR AIR LEAKS Turn the ignition off. Remove the Inlet Pressure Sensor. Connect smoke machine 84-04 to the Inlet Pressure Sensor port in the intake duct and begin injecting smoke into the intake system. Observe all intake system components for evidence of smoke leakage. Is there evidence of smoke leakage? Yes >> Repair or replace as necessary. Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING). No >> Go To 6 6. BOOST PRESSURE ACTUATOR Turn the ignition off. Replace the Boost Pressure Actuator in accordance with the Service Information. NOTE: Ensure the ECM and Boost Pressure Actuator harness connectors are connected. Test drive the vehicle. With the scan tool, check for this DTC to set again. Did this DTC set again? Yes >> Replace the Turbocharger assembly in accordance with the Service Information. Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING). No >> Replace the Boost Pressure Actuator. Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING |
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| Author: | pappyrsg [ Thu Oct 04, 2012 9:07 pm ] |
| Post subject: | Re: Throwing Overboost P0234 code as accelerate through abou |
Will try Italian Tune Up tomorrow... a couple beers down right now. I have the service / repair manual pdf... have run through troubleshooting, but not clear how to check for air leaks (that's why I asked about soapy water testing), or how to duplicate 'smoke test' at home... nor how to 'check boost control vacuum supply' (it most certainly is generating vac and moving 'waste gate' actuator... as seen by pulling/reattaching vac hose to that component and watching shaft... but may not be moving full stroke... of course this is just at idle). |
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| Author: | papaindigo [ Fri Oct 05, 2012 8:33 am ] |
| Post subject: | Re: Throwing Overboost P0234 code as accelerate through abou |
The usual way to check for leaks in the 2 intercooler hoses is to pull them off the vehicle; remove the woven covering if present; look for holes/tears or if the hose(s) are so soaked with oil as to be mushy if either is the case replace (I like Samcos). In theory you could remove the "engine" end of each hose; plug one end; plug the other with something that has a air hose fitting and then LIGHTLY pressurize the hoses and the intercooler at which point you could check for leaks with soapy water. I wouldn't bother with the latter unless you suspect leaks in the intercooler itself; something that's be known to happen of a few vehicles. Our turbo's don't have a waste gate rather they have movable vanes controlled on the stock turbo by vacuum. The check for proper movement per GDE is "You can check the vane functionality at idle in park. Underneath the vacuum actuator on the turbo is rod extending downward connected to the vane mechanism. If you pull off the vacuum line at the turbo, the arm should drop about 1/2 inch and then raise back up after reconnecting the vacuum line. It is a bit difficult to see the rod, but this is the easiest method to check for proper VGT vane moevment." If there is insufficient movement the usual solution is an Italian tuneup and in extreme cases there are other methods. |
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| Author: | pappyrsg [ Fri Oct 05, 2012 10:55 am ] |
| Post subject: | Re: Throwing Overboost P0234 code as accelerate through abou |
Thanks for the info folks... thought there was no real 'waste gate'... that's why I had it in quotes. On the Italian tune-up.... would it be better to do that with the EGR disconnected? |
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| Author: | papaindigo [ Fri Oct 05, 2012 11:07 am ] |
| Post subject: | Re: Throwing Overboost P0234 code as accelerate through abou |
Doesn't matter |
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| Author: | pappyrsg [ Fri Oct 05, 2012 1:06 pm ] |
| Post subject: | Re: Throwing Overboost P0234 code as accelerate through abou |
Italian Tune Up went falsetto... after several acceleration repeats, over-boost code seemed to have stopped, then tried a couple more times and came back, went to try one more time and as I set up for the run, heard whine from engine compartment... turbo? Pulled over and found any engine rev yielded very loud high pitched whine, lower pitch if I let it idle, then would stop completely as idle settled. Left engine run for a good 20 minutes to cool down, temp got down from just a little above normal to a bit below normal operating. Whine still there... limped home the 3 miles or so at 10-15mph, keeping the whine to a barely discernible low pitched tone or nothing... any attempt to speed up or climb ANY hill led to higher-pitched louder whine. My thoughts... oh crap, Italian tune up actions (10-15) burned up turbo bearings... but another possibility, had a leaking hose and now it's leaking enough to sing... looking. Thoughts... advice? |
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| Author: | pappyrsg [ Fri Oct 05, 2012 1:32 pm ] |
| Post subject: | Re: Throwing Overboost P0234 code as accelerate through abou |
EUREKA !!! As I disassembled intake area hoses, main pressure hoses (Samco) still look good, but the stock intake big molded hose came apart at the clamp. It was literally rotted at the hose flange, likely from 7 years of oil and soot deposits... darn EGR! Anyway, now the question is... Is this something I must get from the Jeep dealer, or does someone like Samco make a better version. I'll start the internet search, but a jump start from anyone out there would be greatly appreciated. By the way, the turbo wheel looks good and has no discernible slop. |
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| Author: | papaindigo [ Fri Oct 05, 2012 3:20 pm ] |
| Post subject: | Re: Throwing Overboost P0234 code as accelerate through abou |
Samcos should last forever so long as you are careful to make sure they are not rubbing on anything (pay close attention to the sensor on the side of the air box and what I think is a gray AC sensor low on the driver's side next to the hose. Don't godzilla the hose clamps on the plastic intercooler ports just make sure the hose and the clamps are all the way onto the plastic port then run the clamps down good and snug and recheck after a couple of days. The airbox to turbo hose is dealer only (PN 53013104AE) and not too pricey; ca. $60 IIRC. There has been some discussion about a better product, possibly Samco, but nothing has come of the discussion that I know of. WARNING from sad experience; the clamp on the airbox end of the hose is fixed to the hose so it's extremely important that you take care to work the new hose all the way onto (touching the MAF sensor) the plastic airbox outlet before tightening the clamp. Failure to do so WILL result in a crushed airbox outlet as geordi and I both know. |
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| Author: | pappyrsg [ Fri Oct 05, 2012 3:38 pm ] |
| Post subject: | Re: Throwing Overboost P0234 code as accelerate through abou |
Thanks. I ordered Mopar intake hose part from Pollard Mopar Parts in Boulder, CO... $45.08 + shipping... best combination of price, shipping cost and shipping time to AZ. I found the part at various places ranging from $38 to $90+, plus shipping or sales tax depending on whether bought in my home state. Tried to get local dealers to drop down to a more reasonable price range, but still that old high price American car dealer attitude. In the end, the Italian tune probably wasn't necessary, but at least in stressing the turbo doing it I uncovered the real problem. Thanks again folks. |
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| Author: | jlgail4309 [ Fri Oct 05, 2012 8:27 pm ] |
| Post subject: | Re: Throwing Overboost P0234 code as accelerate through abou |
I went with the factory hoses as well. They worked on mine for a 130000 miles. I thought how about a 130000 more. A little over a 100.00 bucks. Glad u got it fixed. These our great little trucks. |
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| Author: | pappyrsg [ Fri Oct 12, 2012 8:04 pm ] |
| Post subject: | Re: Throwing Overboost P0234 code as accelerate through abou |
Well, unfortunately, I still have the whine and 'whistle' after replacing the torn / decomposing intake hose. Haven't tried running it up to speed, afraid of complete failure and ramifications from that. Any ideas? |
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| Author: | Goglio704 [ Fri Oct 12, 2012 8:23 pm ] |
| Post subject: | Re: Throwing Overboost P0234 code as accelerate through abou |
If you have a hand vacuum pump, hook it up to the the vacuum actuator on the turbo. This is the vacuum canister that changes the geometry of the turbo to control boost. With the engine off, apply vacuum to the actuator and pay attention to repeatability of travel at various vacuum levels. Look for sticking and the like. Worst case, you exercise the mechanism without taking a chance on overboost. If there is anything you can lube externally in the linkage, I'd do it, but I would not spray anything in the turbo vanes. |
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| Author: | jlgail4309 [ Fri Oct 12, 2012 8:38 pm ] |
| Post subject: | Re: Throwing Overboost P0234 code as accelerate through abou |
I could hear the turbo a little after i fixed the the hoses. Do u still have the codes. |
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| Author: | pappyrsg [ Fri Oct 12, 2012 8:47 pm ] |
| Post subject: | Re: Throwing Overboost P0234 code as accelerate through abou |
Did the vacuum test while troubleshooting overboost. Same results now... about 23lbs of vac to get full motion of actuator. It holds there (no leaks). I can back off (or ramp up) to about half actuation at about 15lbs. Appears to be consistent action through stroke once it gets above about 10lbs... no significant movement at all below that. I will say though, the stroke (shaft) never really seem to go to full stop (bury the adjustment nut). (By the way jlgail4309... as I mentioned... too many possible negative consequences, with this noise, to run her up and see if the overboost code is gone.) |
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| Author: | GreenDieselEngineering [ Fri Oct 12, 2012 8:54 pm ] |
| Post subject: | Re: Throwing Overboost P0234 code as accelerate through abou |
How much visual movement of the nut on teh turbo actuator arm do you see? It sounds like the vanes are not opening up enough due to a blockage. |
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| Author: | Goglio704 [ Fri Oct 12, 2012 8:58 pm ] |
| Post subject: | Re: Throwing Overboost P0234 code as accelerate through abou |
Personally, at this point I would disconnect the vacuum line to the actuator and take a test drive. It should be a real dog. If it isn't, the turbo is generating boost without being asked to. Yes? |
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| Author: | pappyrsg [ Fri Oct 12, 2012 9:04 pm ] |
| Post subject: | Re: Throwing Overboost P0234 code as accelerate through abou |
Total stroke is just a bit more than the thickness of the nut... I'd say about 5/16 inches. |
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| Author: | Goglio704 [ Fri Oct 12, 2012 9:07 pm ] |
| Post subject: | Re: Throwing Overboost P0234 code as accelerate through abou |
It has been a few years since I played with it, but that sounds too little. GDE is, of course, the definitive answer... |
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