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86 olds delta 88


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jolynett
New User

Jan 11, 2009, 2:48 PM

Post #1 of 4 (2241 views)
86 olds delta 88 Sign In

transmission will not change gears when driving staying in 1st gear if anyone knows what it could be please let me know


Tom Greenleaf
Ultimate Carjunky / Moderator
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Jan 11, 2009, 3:21 PM

Post #2 of 4 (2235 views)
Re: 86 olds delta 88 Sign In

I'm groping at a guess and a maybe for you with this:

Look at the throttle body where a cable for throttle goes and another (likely - not certain) that goes down to/over to trans which acts as a throttle position device which might be hung up telling trans your foot is too the floor wrongly which would make it hang on to the lowest gear possible before a forced upshift at pretty high rpm - perhaps up to 40-50 mph or so with engine racing a bit high for an older pup now.

Just look for that cable and see if it's free to return. Other basic checks of course, fluid level, color can be indicative of overall condition.

There's a maybe for '86 that trans actually got info electronically from the actual TPS and you might need some help to determine just what tells it when to shift.

Good luck,

T



blacktop
New User

Jan 11, 2009, 3:46 PM

Post #3 of 4 (2233 views)
Re: 86 olds delta 88 Sign In

I failed to mention that I cahnged the trans is there a relay that controls the shifting or a control module.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jan 11, 2009, 5:06 PM

Post #4 of 4 (2228 views)
Re: 86 olds delta 88 Sign In

I have to defer to general principles of controls for the era.

Shifting is controlled by a valve body which is like a fluid brain if you will diverting fluid under pressure to engage bands to do their magic.

Ok: Shifting is controlled by YOUR selection with the shifter itself and the linkage thereof. From there the "automatic" stuff is sensing thru assorted means, the rpm of the engine (thru a mechanical governor or new would be electronic) the throttle position which can be a cable as mentioned litterally knowing how far you are pushing the gas pedal and many are adjustable, then load on the engine is usually measured by the intake manifold vacuum and might be converted to an electronic signal to tell the trans how hard the engine is working. All that makes a decision on what gear to be in. Only the gear selector you choose will hold a lower gear than even the crude mechanical brains of a typical automatic will allow if and only if all is operational.

In brief if I can: Either the trans thinks just low has been selected OR it thinks load it so extreme it should be in the lowest gear it is allowed OR that your foot is "pedal to the metal" which tells it to hang on to lowest gear allowed by the governor - many are simple centrifugal weights that force an upshift when they expand against spring tension!

Whew! Bear with me - I'm writing this off of memory (what's left!) not some "copy/paste" trick out of some archived something!

OkII: Since this trans has been replaced/changed you need to make sure all linkage is hooked up as well as all wiring. There may or may not be a dedicated vacuum modulator to a diaphragm on the trans in 86 - dunno. The linkage for "kickdown" if left unhooked or broken would usually cause very late downshifts and not this but if broken or stuck could tell trans you are "flooring" it all the time. I'd concentrate on all hook ups being intact first. Watch shifter action by eye with a helper shifting to see it move the full range too and return properly.

Keep at it. I'm not quite ready to say just send it out yet,

T







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