1992 Olds 98 Surging Problems

[TheEvilBain_TDB]

I have a olds ninty eight that is surging when you keep the throttle steady at 45 mph Ive changed the wires,plugs, the whole throttle body with all sensors, cat convertor, oxygen sensor. and its still doing this it also does it up hills if you take it out of over drive it will stop it seems to do it at low rpms

[maxwedge]

Welcome to AF, disconnect the egr, see what happens, confirm good fuel pressure also.

[TheEvilBain_TDB]

Thank you for the welcome. Im going to try swaping the egr valve out (i have a parts car) but wouldnt it be throwing a trouble code at me? Im not getting any trouble codes at all Im also going to look for a vacume leak but then it would surge at all speeds correct

[TheEvilBain_TDB]

Were is the egr valve located. Is it off the intake manifold like most cars. I notice its not the diaphram type when i look the egr up at partsamerica it looks like its a relay type valve

[maxwedge]

You rarely get egr codes on pre 95 cars with obd1, many things can cause your problem, so a quick disconnect is an easy 1st step.

[Jrs3800]

The 1992 Olds 98 had the Tuned Port Injection 3800.... In 1992 this engine did not use an EGR Valve as the engine passed emissions tests with flying colors without the EGR.... GM then found that they were cracking exhaust manifolds and burning exhaust valves... So for the 1993 Model year the EGR was brought back on the 3800..

There could be a couple of issues... Possible slight Vac leak.. Its also possible to have a burnt exhaust valve( compression test should tell you this )

Rule everything out one by one... Also what kind of plugs are you currently using?

I think you have a simple problem, I don't think you have a burnt exhaust valve altho it is possible with the EGR'less 3800 and little brother 3300( also EGR'less )...

Might have anything from a bad injector, to a bad plug, to a bad wire... Even a bad coil/pack.... Hard to say without being there to look at it..

[TheEvilBain_TDB]

LOL i knew i wasnt finding the egr valve for a reason. I changed coil packs went through 2 diffrent sets of wires and plugs (auto lite platnuims the second time) I just put some spendy fuel injector cleaner in it. I notice it only surges back and forth at aprox 43 to 47 mph in over drive or going up hill if i shift it to drive it will clear up. I do notice some cracks in the exhuast manifold but i dont think its leaking i also changed the cat and the all the sensors on the throttle body and the oxygen sensor

[maxwedge]

My bad on the egr guys, should have looked at the application years, good pick up Jrs3800***. Cracked exh. manifold could skew the o2 readings, but it would have to be a big leak. It is possible this could be a trans issue also, possible o/d or tcc enagagement issues. Someone familair with these type of symptoms should drive the car.

[Jrs3800]

Max thats agreed.. iirc the one good thing about the 92 with the 4T60-E and PCM is that a Scantool should be able to display TCC Slip under full lock..

I do agree that someone that knows the GM 3800/4T60-E powertrain should drive the car to see what its doing..

[TheEvilBain_TDB]

Thank you guys for all your help. Ill post an update here if i find out what the problem is to help future members.

[TheEvilBain_TDB]

Well today i changed tranny fluid and filter still now change its not really a surge its more of a jerking back and forth