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My 89 740 GL starts and idles fine, and when I rev it to 1500 rpms, and hold it there, it does fine. However, when I rev it to 2000 rpms the gage immediately starts to bounce down to between 750 and 1250 and back up to 2000. If I let off the pedal then it idles down to about 900. If I try to drive it, it does same thing as the engine seems to turn off then a fraction of a second later turn back on again, and upon releasing the pedal it goes smoothly to idle. The car has 295,000 miles and a very bad rear main seal oil leak. The new things on car include rpm sensor, distributor, cap, rotor, plug wires, and engine temperature sensor. Things that I have swapped from salvage volvo include ignition amplifier, knock sensor, and radio suppression relay, and coil. The OBD codes come up good except when testing throttle position sensor (TPS); I am supposed to get a 3-3-3 when releasing from full throttle, but I get a 3-3-2. I adjusted the TPS according to Brickboard.com, and still get that 3-3-2. Flame trap and throttle body is clean. I still get the bouncing rpm. If anybody can point me in the right direction, I would greatly appreciate it. Thanks!
 

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Re: 89 740 GL with bouncing rpm gage (jesuslor)

Welcome to Swedespeed, John.<p>Scroll around here for answers to this situation...<p><A HREF="http://www.brickboard.com/FAQ/700-900" TARGET="_blank">http://www.brickboard.com/FAQ/700-900</A>/<p>George Dill<p>
 

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Re: 89 740 GL with bouncing rpm gage (jesuslor)

Even thou you replaced the RPM sensor, it is only as good as the CLEAN surface it is sensing the RPM from. If you got 200,000 million miles and a stated BAD oil leak. It might be oil has gotten to somewhere BOSCH or Volvo did not ever intend it to be. Nor for the MAGNETIC RPM sensor to pulse/trip right. Hense your stumble and TACH danceing. Also as a side note a failing 200,000 million mile COIL (swapped or not) might be also a root cause. Coils that you swap out form junkyards (never ever know history or true milage unless you drove the junk car from new that it came out of before) are only to look for the obvious. Such as, will the car start or not since it did not before. For what you got a car that runs bad or funny A NEW COIL is required. And ONLY a new coil, nothing else will work. Unless you get a used one form a used car that is running like it came off the showroom floor then ok. But I doubt you will, so see above. <IMG NAME="icon" SRC="http://********************/smile/emthup.gif" BORDER="0">
 

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Re: 89 740 GL with bouncing rpm gage (Nato740)

Nato740,<br>Thanks for the advice and information. I will fix my oil leak and clean leaked oil. Great advice! Hope this works.<br>John (jesuslor)
 
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