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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: brlarl on August 18, 2009, 09:00:01 am
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I have a 1985 C10 Silverado 2X2 with a 5.7 engine and tranny Combo out of a 1990 Chevy Suburban. Vehicle runs great.............well up until a few days ago. The motor was over hauled about 3 years ago and with the exception of a few small oil leaks it runs good. The tranny on the other hand has not been over hauled and has probably about close to 300,000 miles on it. I know the time is getting closer for me to have to overhaul the tranny but the truck still drives and goes into reverse. Now a few days ago as I'm on the freeway I noticed that it feels like the a/c compressor is kicking off and on (but its not) while driving. While this happens if feels as if the engine rpms is rising and dropping and the truck feels like it is surging back and forth in a forward motion? It does the samething with the A/C off just not as noticeable. Confused? Sorry it is kind of hard to explain. It is almost as if the tyranny clutches are releasing off and on. Can anyone explain what it feels like when a tyranny is slipping? I have never had the pleasure of driving a vehicle with a failing tyranny. I'm trying to eliminate the tyranny as the culprit. The only thing that was done on the day is started driving funny was oil being added. I checked it and it was not over filled with oil either??? What other issues can cause this symptom? Any help? Thanks in advance.
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If it has the 700R4 the lock up torque converter may be disengaging.
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I was thinking about that. It does have the 700R4. Is there a way to find out if it is indeed the torque converter?
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unplug the connector on the side of the trans and see what it does
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Cool, thanks. Now if it is the lock up torque converter, does it mean its the converter or the solenoid or both? How can I tell?
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If you determine that is the cause there are several things you need to check. Let us know if that is the cause and check the TV cable adjustment.
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I will do that and get back to you guys. THanks
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Will a transmission unit from a 1997 Chevy Tahoe switch over in place of the 1990 700R4 currently in my truck?
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Not without the ECM to control it. the 97 uses a 4L60E vs your 4L60 (700R4)
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What years are exchangable from 1990 on? THanks
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1991 and part of 1992
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Do you have a tach so you can watch the rpm's as the engine surges?
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Vile,
Didn't they change the 700R4 after 93 and then started to call it 60LE
Steve
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Late 92-93 the 4L60E was being produced. 93 up would be 4L60E and can be easily identified by the connector on the trans. The 4L60 is identical to the 700R4 just renamed presumably due to the bad rap it had gotten in the early days.
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Yeah I have a tach and I noticed on the ride home yesterday that the RPMs were not jumping during the time the truck was surging. I had my check engine light come on this past Sunday and went off once I shut the truck off and has not been back on. I checked the system and got code 032 which is "Incorrect EGR Flow" could this possibly be the culprit causing my surging? I did also notice that while the rpms rise just before shifting to the next gear is when I feel the surging then once it goes into the next gear I don't feel it again until just before it shifts again. Once it is in OD I can't say that I feel it. Also if the A/C is on it is A LOT more noticeable. When the tranny is in OD and the brake pedal it is applied shouldn't the RMPs jump up a little meaning the torque converter is unlocking? If so I can't say that I notice mine jump up. In OD I'm running at about 1200 RMPs according to my tach. Any Thoughts? Thanks
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OK guys, I pulled the lock up plug off the tranny drove it and it did not change anything. Now I honestly do not think it is the tranny. I noticed the idle is rather low. Even with the A/C on it idles low, if I turn the A/C off the idle does not change. I unplugged the IAC and no change either. Since there is no idle speed control on the TBI, what controls the idle when the A/c is on? I still have the surging when I drive, but if I romp the throttle the truck will pick up and move but surges slightly. The truck has a new fuel pump. I rebuilt the the TBI about 5-6 month ago and delivers fuel great. I did a full tune up about 2-3 months ago. My compressor is acting up, can this cause anything? I have not noticed by MPGs drop yet. Any Ideas what may be causing this low idle?
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Since there is no idle speed control on the TBI, what controls the idle when the A/c is on?
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The idle air control motor
Check and make sure ALL of your ignition components are in good shape. If you haven't done a tune up recently then do one. Check for vacuum leaks at the base of the TBI unit. Then check the TPS.
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I have done a tuneup about 2-3mnth ago and I have recently rebuilt my TBI. Last night I unplugged the IAC and drove the truck. I can't say that I noticed any difference when I drove it. If either the TPS and the IAC is bad why wouldn't it trigger the Check Engine Light? I also noticed last night that my a/c compressor clutch is starting to stick. When in idle and the a/c is on the clutch is spinning then it slows down to a near crawl (as if it is skipping) then spins fast again. Could this cause the surging that I feel when I drive? Sorry for all the questions, I'm just tryin to figure out why it went from running fine one day to acting up the next. Thanks Again
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Turn the defrost off. The IAC is for IDLE only so it won't make a difference. Even though you did a tune up you still need to check the components. Unplug the TPS and drive it.
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Cool, I'll try that. Do the sensors have to be completely bad before the "Check Engine" light comes on? Thanks V
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OK so I pulled the TPS plug off and drove it during lunch today. The truck drives better and picks up better but the surging is still there not as bad but still there? I still need to check the componets in the distributor but the cap rotor and wires are all good. Had time during lunch to check those. Any other suggestions? Thanks
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Did you spray carb clean at the base of the tbi? The check engine light doesn't come on because a sensor is bad.
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No I didn't spray the base but to make sure the truck runs good for years to come I went ahead and changed the TPS and the IAC to new units. The truck runs A LOT better but I can still feel the surging just not as much. I did find the back screw on the distributor cap loose and the contacts with some build up. I tightened the cap and cleaned the contacts. While there at the distributor I checked everything and all was good. Any more suggestions? Does any one know if I can find a new Engine harness? I would like to change the whole computer harness for the engine. I did find some brittle wires on the current harness and fixed them but would like to change it to a new one. Thanks Guys.
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You have suggestions you haven't tried and are now parts changing. Try doing everything suggested first.
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OK so I sprayed the base of the TBI and it did not make a difference. After I sprayed it, I re-torqued the TBI and sprayed again just to make sure......still no change. Should I focus on the fuel system? Any other suggestions V? Thanks
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Any othe suggestions? Anyone? Thx
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Did you check your plugs? Is the EGR functioning properly? An EGR valve that flows at idle will cause your idle to be low.
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Yeah the plugs, the EGR Valve and the EGR solenoid were checked all are OK. Actually my idle is OK since I changed the IAC and the TPS but again I still have that darn surging. Could the fuel pump or fuel filter cause the surging? Thx
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Yuppers, could be. I woulda thunk it would have tripped a lean code. Might try changing the fuel filter if it hasn't been changed in awhile just as a good measure anyhow.
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I need help from anyone that may know why my truck is surging. Can the transmission cause the surging? I did what Vile said to do and all was fine. I changed the TSP and the IAC. I just changed the fuel filter. I seems everything that I change seems to make the surging less and less. I have no lights on and the temp is at 195 -205. The truck does move when the gas is stomped on and there is no hesitation but I still slightly feel the surging. Any and all help is appreciated. I need to fix this thing right since it is my daily driver and my only vehicle to get around. Thanks Guys
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pinch off the return hose and drive it. Report
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I'm sorry, are you refering to the return on the fuel system or tranny? Thanks ???
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:-[
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I'd suspect fuel as it wouldn't be very beneficial to clamp off a transmission line. Also try disconnecting your ac clutch.
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LOL, Yeah I guess that make sense. I have disconnected the Clutch from the A/C, nothing changed. Vile I have steel braided hoses at the TBI (OEM) and hard lines down under the truck. I obviously can not pinch off the hard lines but will I damage the steel braided lines if I pinch them off? If I can ask what will this do? I'm curious. Does it raise the pressure in the system? Thanks
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It won't damage them unless you are pinching them off with wire cutters. It raises the pressure at the TBI.
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LOL, Thanks Capt. I'll try that tonight and report back. Thx