Transmission – Intermittent Hard Shift w/ Check Engine Light?

[Texast224]

I have a 1995 Tahoe, 4x4 with 5.7L 350, has 285,000 miles right now. I wanted to see if anyone else is experiencing a similar issue that I’m having.

I get an intermittent hard shift out of first, but only when my check engine light comes on.

Most of the time it runs fine, with no problems. But when I start my engine, if the check engine light comes on at the same time, I will have a hard shift out of first. If I start my engine and the check engine light does not come on, which is probably 4 out of 5 times – it shifts just fine.

And I do get a check engine light after I’ve been running it awhile on the highway (code 032) but that is just my EGR valve, and shifting is fine.

The shift problem is only when I start up and check engine light is on from the very beginning.

I can shut the truck off for 10 seconds or so, start it back up – and if the check engine light has gone away, it will shift just fine.

Transmission was rebuilt at 160,000 miles – so 120,000 ago.

So do I have a mother board problem? Does a 1995 Tahoe transmission have electronic solenoid or something?

Thanks – this has been very frustrating because no shop can seem to find the code or recreate the issue.

 

[ccapehartusarmyINF.(ret)]

could be yer throttle position sensor? a bad one can cause wierd shifting issues

 

[SunlitComet]

the tranny maybe acting up because the fuel system is reacting to the egr problem. this may cause disruption of other functions. it is also possible that the tranny maybe getting a max line pressure command as a result of the egr system malfunction. it all depends on how the system reacts to what is sees and what it expects to see. the tranny may see the after effects as slippage in the tranny which will cause the same results. I strongly suggest you fix the egr problem right away before it causes some permanent damage somewhere.

 

[ccapehartusarmyINF.(ret)]

so problems with the egr system can have an affect on the tranny?
lol i probably wouldave chalked it up to coincidence

 

[SunlitComet]

it might be but when you have an obvious fault and try to fix what may be a side effect of it instead of the original issue you are just ignoring the problem. the egr system needs to addressed first not the tranny. and yes the tranny uses electric solenoids inside of it.

 

[southboundchicken]

it might be but when you have an obvious fault and try to fix what may be a side effect of it instead of the original issue you are just ignoring the problem. the egr system needs to addressed first not the tranny. and yes the tranny uses electric solenoids inside of it.

I agree.... I had a bad mass air flow that caused hard shifting so i would definitely fix what you know is wrong...

 

[ccapehartusarmyINF.(ret)]

lol yeah i would fix the obvious fault first but i just kinda figured that goes without saying

 

[Texast224]

I def need to change the EGR - makes sense to eliminate stuff that is a known problem to help isolate the underlying issue.

Other things that Ive found that could cause a problem:
Throttle body base gasket - sucking air causing high idle and hard shift
TCC value wear issue
Throttle Position Sensor
Upper and lower intake manifold gasket (mine actually needs to be replaced - was told leaking coolant)

anything here seem like the most likely culprit?

Thanks for the help.

If nothing else will replace EGR first, then start knocking em down one at a time (cheapest first) and see what fixes the issue.

 

[SunlitComet]

perform the test procedure to isolate the fault in the egr system first. it may not be the egr valve itself but instead a broken hose or solenoid. you can spray some starting fluid around the manifold and tbi base to check for engine disturbances. if the manifold is leaking coolant. get on replacing it. if it gets in the engine oil you can kiss your bearing goodbye or ruin the plugs and converter if leaking in the the cylinder somehow.

 

[Texast224]

Update:

Replaced EGR valve, ERG solenoid, MAP sensor, idle air control valve, engine temp sensor, and gave her a tune up (MSD 8.5mm wires, rotor, cap, delco plugs). Ran fine with no recurring issues until today - same issue happened once.

Started up fine early in the am. Leaving work started up and got the check engine light with hard shift into first and rear. Turned it off and let sit for 30 seconds or so, started back up and no check engine light, not hard shift.

Before I started replacing stuff, I would notice that if my truck sat in the sun all day at work, I would almost certainly have this issue. In the early am when it was cool - i never had the issue.

Throttle position sensor maybe?

Got another question - anyone know where I can find a replacement gasket for a K&N cold air intake kit? Mine is cracked and may not be sealing as it should.

Thanks for the help.