engine acting funny

i have a 95 riv with 71k on it. Ive noticed recently that at around 60mph and lower, my engine is acting funny when im not in the gas. when im barely in the gas at any speed it seems hesitant. When im cruising down the street say at 30 mph, i can hear, feel and see ( the tach that is) drop slight rpm and pick it self up again immediatly. The way my exhaust is, i can hear it real well and its magnified. But if i mash the gas, it takes a second to catch then its like a bat out of hell.

First I would change the Fuel Filter. Next I would check the wires for a crack. It sounds fuel related. I know there are many here who can help. Hang on a while and I'm sure you'll get some more responses.

I would also check for any bad vacuum hoses. Vacuum leak could be cause of problem also.

is this something you just noticed or is it the result of something?
ie: new mod, bad gas, maint item done, etc.
all that have been mentioned are a good start. do you have and SES light for misfire or anything else?
may want to try cleaning the MAF, checking the plugs if they are old, and get back to us.

Do you have a check engine light? Sounds like it could be a temp sender, TPS, something along those lines.

no engine light, been going on a few weeks. pretty sure not bad gas, have a new fuel filter, ill check the plugs, i installed them last summer. Ill check hoses and wires and clean the maf and get back to ya

Rickw wrote:

I would also check for any bad vacuum hoses. Vacuum leak could be cause of problem also.

This was my first thought.

ok wow i havent been on here in a while, been very busy. Well heres some updated info on this thread, I checked all visible hosed and didnt find any vaccuum leaks. I cheacked the plugs and they are still ok. My engine light comes on at random now, probably 6-8 times in the last 2-3 months but when i try to get it on a computer, i cant make the light come on, The hesitation now seems pretty bad when i feather the throttle leaving in first gear ( all the time) but if i leave with moderate to heavy throttle no problem. Also idle is perfect and if i give it gas in park or neutral, no problem either. It happens under a load i guess. Could it be the transmission? or the throttle body? I cleaned the Maf also and no problem.
thanks for your hekp guys

without re-reading the thread i'd suspect plugs and wires. they may look ok, but not act right under load. plugs are super cheap and easy to replace, if only to rule them out. wires are not that expensive either, but make certain to get acdelco wire b/c other dont normally work well in our cars.

maggot wrote:

My engine light comes on at random now, probably 6-8 times in the last 2-3 months but when i try to get it on a computer, i cant make the light come on,

Could you elaborate? Have you actually gotten a scanner plugged into it?
Even if the light goes out, the PCM should still store the code for a couple dozen ignition cycles...

(Boy, that's the smartest thing Cadillac did, and the dumbest thing no one else did, when all this computerizing began: If the light came on, all you had to do was punch up the trouble codes on the Climate Control display.)

Eldo wrote:

(Boy, that's the smartest thing Cadillac did, and the dumbest thing no one else did, when all this computerizing began: If the light came on, all you had to do was punch up the trouble codes on the Climate Control display.)

aside: don't forget the '86-'89 Riv with the CRT - you could use the CRT to view all trouble codes and even raw sensor output, a full diagnostic machine!

Oh ok i did not know the code was stored even after the light went off. I do not have a scanner, but i have got to the local auto parts store and they have one ppl can use. whether i didnt know how to use it or it was broke, or not the one for my car, i couldnt get it to work, I kept getting an error sayiong it could get a resposnse from the computer and i needed to check the connection.

The '95 SC motor uses OBD-1.5, which the auto parts stores scanners generally cannot scan. Their cheap scanners are OBD-2 only. You'll have to pay a shop who has an appropriate computer to pull the all important codes for you.

Derek is right. You can't believe the bundle of cables & cartridges necessary to get into all the different computers... I would think the worst possible damage would be $50 for a shop to get the codes out for you, and if they do the repair, they'll often reverse the charge.

Hey guys i just removed my throttle body from the car and its is horribly filled with gunk. The valve inside is sticking REALLY BAD and it takes a bit of force to open it. You think this might be the problem as to why when i feather the throttle or tap it, it hesitates or tries to stall because it cant open the valve. Heres a link to what i posted earlier about cleaning it. https://rivperformance.editboard.com/series-i-engine-transmission-f13/throttle-body-cleaning-t6588.htm#96046

maggot wrote:

Hey guys i just removed my throttle body from the car and its is horribly filled with gunk. The valve inside is sticking REALLY BAD and it takes a bit of force to open it. You think this might be the problem as to why when i feather the throttle or tap it, it hesitates or tries to stall because it cant open the valve. Heres a link to what i posted earlier about cleaning it. https://rivperformance.editboard.com/series-i-engine-transmission-f13/throttle-body-cleaning-t6588.htm#96046

Absolutely sounds like the problem. Clean it, but remember to remove the MAF sensor and to clean it separately and gently with MAF-specific cleaner. The TB itself you can clean with any carb/choke/throttle body cleaner.

Are the fasteners that hold the TB in place Tamper Proof Torx ??????
I think I have absolutely every tool I need except a set of those.
If so, I need to add a rack of them to my toolbox.
I'll request a Sears special XMass gift.

Rick, I think ours ('98) are tamper proof torx. I bought a set at autozone, cheapies that I'll seldom need. I think it's an "E-4" or "E-6" instead of the normal T-4 or T-6. I know I needed an E-4 for something, maybe it was the ignition switch.

I've got a Master Torx Kit that has the standard "T" bits and "E" bits.
But I thought the Tamper Proof ones were different in some way. ?????

Never mind i just looked closer at the row of Male "T" sockets that appeared to be duplicates of the other T sockets, but they have a hole drilled in the center. That's what I would consider Tamper Proof.

Tamper Proof, or Security Torx, are regular male Torx drivers with a hole drilled in the end for the 'security post' in the middle of the female screw head... Now, which is it on the car? (Oh, and are we talking TB or MAFS?)

I'm not sure what the TB and/or MAF is secured with, but either way I just realized I have all the necessary bit's regardless.

The reason IDK what it requires, is because I paid my buddy down the street with the MotorVac to clean the Intake, TB, MAF and everything else at the same time.

This time I'll do the basic cleaning myself now that I have installed Cleaned and Flow Matched injectors a few thousand miles ago.

Since I was going to go to the parts store and follow my own advice about doing a quick swap of my rubber-seal-only thermostat back to 195* for the winter, I popped the FI Sight Shield off and checked out the TB... The TB itself is fastened with regular hex nuts, but the MAF & TPS sensors use the center-post Security Torx, what looks to be about a ST-25. As long as I already have 2 cans of CRC Electronic Parts Cleaner, I'll see if I can buy one individually at the store.

Well that was a pain in the ass...

Turns out there are 2 different Torx security bits: Regular 6-point Security, and Torx Plus (TX) that has the center post but only 5 points!

Our cars use the 6-pt T20S...

Eldo wrote:

Well that was a pain in the ass...

Turns out there are 2 different Torx security bits: Regular 6-point Security, and Torx Plus (TX) that has the center post but only 5 points!

Our cars use the 6-pt T20S...

I never understand why they do such things.
Do we really need two different sets of tools to do what one will accomplish. A Torx Security bit and a Torx Plus
A 5 point and a 6 point. Senseless if you ask me.
And some people wonder why the independent mechanic has to charge the labor rates they do. Just consider the investment in special tools to work on ALL makes of cars. Each with there own unique tooling needs.

For most such bolts (5 or 6 point Torx security heads) our local Valu Hardware, Home Depot and Lowe's sell replacement screws with allen or hex heads.

There is some stuff they don't have - such as exhaust studs. Saw a nice Dorman kit today for the pre-metric GM carsthat included zinc plated studs and brass nuts. What I wonder, though, is do the brass nuts loosen themselves from vibration?

By the way - any of you used brass nuts on an exhaust build?

Albertj