New to me old to the world, TS - pile of problems, can we solve them?

[Virgis007]

Hi guys, Pontiac Trans Sport owners!
I'm new to the forum and decided to register because I saw loads of great info and friendly people helping out.
Long story short, I was looking for a cheap some kind of a van, to carry my garage stuff, maybe my family, or family stuff or all together and so on.
Wanted something with a bigger petrol engine sounding nice also, so found this 1993 3.8 TransSport for only 350euro with a valid technical inspection for almost two years (makes the car road legal in my country), so I can drive around with it dealing my stuff carying, also fixing it up on my free time to get ready for the next technical inspection (hope I'm keeping it and fixing, not selling it, because of some deadly expensive fixing prices). I'm kinda handy, doing lots of the work on car my self, so the costs goes only on parts (mostly). Hope I can keep it up with this Pontiac.
So probably because I got it so cheap, there are some problems. The question is what could the reason of the problem be, how much hand-hours it takes to fix, and is it expensive? Hope you guys can help me up a bit with hints and info.
So here we go:
1. The transaxle vibration, when it engages to torque converter (as I understand that is the last gear, because I can feel when you drive on straight road, the rpm drops, the gear shifts to the last one, and then the vibration starts). The vibration is really big, everything starts shaking, like you would be driving on a non asphalted road, or with lots of deep but small holes in line with the wheels. Some times it depends on the speed, the vibration might be not that bad or even bigger, but it is still there. Is it a sign that the trans axle is dying or it is possible to fix some how not so expensive?
That's it for the first time, next problems coming up after solving this one.
And sorry for my English, not my native language!

[Virgis007]

Going to post the second question, because I need a quicker answer, if anybody can advise.
I think the Trans Sport has a CAT (catalytic converter). I am having some ideas, that because the car is quite old, the CAT probably was never changed, and never cleaned, so maybe it is stuck, because in my opinion such engine 3.8 should be accelerating and running real fast, now the engine feels kinda like, you know, choking, I mean, not like real choking, but like it works hard, like the exhaust doesn't have a good exit, and the engine can't put it's real power. Also, I am going to change the spark plugs of course, because they haven't been changed for a long time, and by the time I'll try to measure the compresion on it (hopefully I can reach those spark plug holes on the firewall side...). But would it be worth cutting out the CAT, and puting a straight pipe in it's place? Would the fuel consuption raise as hell? Would some engine electronics start to fail or go out of balance because of cut out CAT?

[Blue Bowtie]

Welcome Aboard!

There are several reasons that shudder can occur when the torque converter clutch (TCC) engages, expecially at lower speeds. It would be a good idea to check the spark plugs, plug wires, and coil packs first to verify they are intact.

Removing the catalytic converter should not cause any operational problems, but if there is a second oxygen sensor in the exhaust pipe following the converter, the ECM may recognize that the converter is not functioning and set an error code. If there is no sensor downstream of the converter, the ECM should not react to the converter being removed.

[Virgis007]

Thanks for the quick reply!
So if there is no sensor after the CAT I'm going to cut it out. But before cutting it out first, gonna check all the plug stuff you mentioned.

[Jeffrv]

Try a test drive next time with the gear selector in the D position, as opposed to the OD. I believe this will prevent the torque converter clutch from engaging, which may pinpoint your problem. How is the condition of the transmission fluid, it is a bright red, or burnt brown colour? does it smell burnt or feel gritty when you rub a sample between your fingers? And is the quantity ok?
Jeff

[Virgis007]

Thanks, going to check those two things also.

[Jeffrv]

Before you go off changing or removing parts, perhaps it might be a good idea to do a bit of diagnosing. Check and change if necessary the plugs. wire, pcv valve etc, a general tune up.
With a 1993 model, I think you may be fully OBD1 compliant, and can use the paper clip trick to retrieve any stored trouble codes in the PCM ( engine computer). This website shows you how.
https://www.troublecodes.net/gm/
Key off, insert paper clip between the 2 terminals, turn key on, BUT DO NOT START THE ENGINE.
After a few seconds the check engine light will begin to flash, in a series of somewhat rapid flashes with pauses. They will be 2 number codes, with a longer pause between codes if there is more than 1 code present. For example if you had codes 23 and 34 stored ( not sure what they are just using as an example) you would get 2 flashes, a brief pause, 3 more flashes, a longer pause, then 3 flashes, a pause, then 4 flashes

[Virgis007]

Originally Posted by Jeffrv

Before you go off changing or removing parts, perhaps it might be a good idea to do a bit of diagnosing. Check and change if necessary the plugs. wire, pcv valve etc, a general tune up.
With a 1993 model, I think you may be fully OBD1 compliant, and can use the paper clip trick to retrieve any stored trouble codes in the PCM ( engine computer). This website shows you how.
https://www.troublecodes.net/gm/
Key off, insert paper clip between the 2 terminals, turn key on, BUT DO NOT START THE ENGINE.
After a few seconds the check engine light will begin to flash, in a series of somewhat rapid flashes with pauses. They will be 2 number codes, with a longer pause between codes if there is more than 1 code present. For example if you had codes 23 and 34 stored ( not sure what they are just using as an example) you would get 2 flashes, a brief pause, 3 more flashes, a longer pause, then 3 flashes, a pause, then 4 flashes

I forgot to mention before, about 2-3 weeks ago I did the paperclip diagnostic test as by the founded info in this forum, because the check engine light was on. So I got the codes:
12 (that code is not a fault as I understood, it's just the diagnostics start code..?)
22 (Code 22 Throttle position sensor error (signal low))
42 (Code 42 Ignition bypass circuit error)
43 (Code 43 Knock sensor error) maybe this code has something to do with the transaxle vibration problem?
I didn't do the test again after that, hopefully there are no new fault codes, but will check.
Did a test drive today to work, to check about the vibration in the D not OD. It still occurs. But as I said it occurs when going on a straight road out of town. When I accelerate to the wanted speed, then I release the pedal (to keep the speed) then it goes smooth, and for egzample if there is 3k rpm, the rpm needle is just a milimeter above the 3k rpm, then it drops to about a milimeter below the 3k rpm and the vibration occurs. Did accelerate up (the gears shift up - no vibration) to about 140kmph, when keeping the speed, accelerator pedal released a bit, again something engages in the transaxle, maybe the torque converter (as I think?), and the vibration is again there, all the same, but at higher speeds, like this 140kmph the vibration feels way less, but is still there. So the slower you go, the bigger the vibration. Did a quick check on trans fluid, when parked. The color looks like burnt brown... Probably not good.. Forgot to smell.. And did check in P but engine turned off. As I read on the measure stick, it should have been in P, engine idling and car leveled. With engine turned off, the trans fluid level was way above the mark. Will check again with engine idling.
Also, the acceleration of the car, gear shifting, and driving felt the same with going in OD, or D. Maybe something is not engaging in the trans or some computer/brain as it should?

[Jeffrv]

I think manually placing the lever in D will prevent the TCC from engaging, which is the test I wanted. Since there was no change, perhaps the transmission is not the problem.
I have had driveline vibrations in the past on mine, and every time it was wheel or tire related. Loose wheel nuts? Bent rim? On 3 separate occasions I have had tires break their steel belt internally, and the tire flops all around. In addition wheels out of balance will cause shaking. Perhaps change the rear tires to the front and vice versa would be a quick and cheap test. You can also see if there is any corrosion on the mounting surfaces on the back of the rim and the hub, and on the wheel nuts. Aluminum alloy wheels are very prone to corrosion, more so than steel wheels.
Have you done any work on the van to address any of the trouble codes?

[Virgis007]

Thanks for the advices and opinion, but I really don't think that the vibration is related to the wheels but still, I might try swaping rear tires with front ones, just to be sure. Why not related, because wheel vibration would be there just as I would reach the speed at witch the vibration occurs, but now, the vibration occurs only when something engages in the transaxle, if I step on the accelerator pedal, or I releas it, at any speed if the thing in transaxle won't engage, there is no vibration at all.
A new question. My TS has an LPG system installed, but it won't work. Can you guys tell me where is the fuel pump wiring located, or maybe where is the wiring routed? I need to find the wires of the pump, and the connections of it, need to unplug it for a quick test of the LPG. Now it's quite expensive to ride around with petrol...
This weekend did a look underneath the TS, cleaned my garage so I could park it and check it from under. Was not so happy with the findings... Quite a lot of rust on the bottom, the side skirts (is that a right name?) are rusty, have holes, all the engine and transaxle have loads of oil on them, but no actual/fresh leaks found. Checked the CAT, it doesn't have any connections before and after it, so everything's in the front (around the engine). Front brake disks are real rusty, also feeling a little bit of vibration when braking, but I think that this is not related to the transaxle vibration also.
Checked local adverts and found a 3.8 TS transaxle for sale, gonna make a call on that for how much, might be useful in the future. I'm kind a "manual" guy, this is my first automatic, so what should I check on a removed-from-auto transaxle before buying it, if possible, not to buy "beated junk", can you advice..?

Nope, didn't do anything yet related with the trouble codes.

[Virgis007]

A little update.

Went to a local shop yesterday, and the guy didn't have at the spot, but even didn't know where to order from such spark plugs for my Pontiac... So I ordered them on the internet, hoping to receive them this week, and hopefully they will fit. I'll try to find some time on the weekend to change the plugs also by the same time to do the cylinder compression measurement. Found for sale 3.8 TS 1994 transaxle, and wants for it only 70 euro, so probably going to buy it to have as a spare, maybe in the future I can do something out of two transaxles.
Also I read some article on Facebook, it was about later (after 1997) GM 3.8 transaxles. To be short, the article said, that the throttle position sensor might have something to do with the transaxle, and I have this trouble code on mine. So I have to find where this sensor/part is and check it out. Quite a bad thing, that I don't know yet, where all the sensors are on the TS, so my main task now is to gather info on the sensors, on what they are responsible for, and then I can (hopefully) start figuring out/pointing out my problems, their locations, and do a plan for works needed to be done + parts searching. Already checking local stores for Pontiac TS 3.8 parts, no good yet, because not so popular in my country (EU, Lithuania), so might be quite a big deal getting/finding/ordering parts. But we will see in the future, no need to worry yet I guess..
Also a good thing, found a repair manual book on the internet localy for sale very cheap, so buying it instantly.

[Jeffrv]

Glad to see some progress is being made. As far as The LPG system, that is not a factory system, but a one off installation. Most dual fuel installations have a toggle switch to go from gasoline to propane, at least any of the dual fuel machines we had at work did. If the propane system doesn't need the fuel injectors to operate, then pull the injector fuse located behind the passengers headlight, this should kill power to all 6 fuel injectors, and both circuits that feed the fuel pump.
TPS sensor is located on the end of the throttle shaft. Page 4 of this article shows you how to test it.
https://easyautodiagnostics.com/gm/3...-of-articles-1
Often however, the issue may not be with the sensor, but rather the wiring leading to the sensor. I have a GM shop manual for my 1995, I don't think there will be a great deal of changes from your 93, except for the EGR. PM me if you like and I can send you scans of the desired circuits.
One paragraph in the shop manual for the 4T60-E transmission notes that often issues that at first seem to be transmission related may be in fact engine related. Any misfiring or poor performance can be hidden by the fluid coupling in the transmission until such time as the TCC clutches engage, and now it is a direct physical coupling engine to transmission. Any shortcomings in engine performance will show up then.
Jeff

[Virgis007]

Thanks a lot Jeff, great info you are sharing with me, and also might be with others who might look up searching for same symptoms.
Yep dual fuel systems petrol with propane has a swich to go on petrol or propane. So the fuse behind the passenger light and by the relays cuts off the injectors and fuel pump, but it doesn't cut the spark plug work I hope? If so it is very good then, I'll do a little test, now i think that the propane brain/computer is not getting any signal and it doesn't show any life signs, going to check it's wiring with multimeter, if I won't find anything, just going to cut it out and do a manual version with simple wires, a three pole switch and some relays. Tested old thing, been done this on lots of german cars with carbs and injections.

Thanks for the info on the TPS, will check that on the weekend to! I hope to receive my repair book till weeked and maybe there will be info on the TPS wiring.

Ohh, thanks for the explanation! Now i got what you mean. Because the transaxle with TCC engagement gets the straight connection with the engine, all the engine incorrectness goes kinda straight to the wheels (not exactly so, but in the case of my situation probably). So lets do it this way first. Let's find out the condition of the engine (the compression), deal with the trouble codes, and when I'm sure the engine is okay (or not) then we will see what to do next, go in the transaxle deeper investigation or no. Seems like a good plan to me, thanks again Jeff.

[Jeffrv]

Virgis, going over the wiring diagrams again, it appears I gave you some incorrect info. That injector fuse also powers a circuit in the ignition module, so interrupting that will in all likelihood prevent the ignition from working. Pulling the fuel pump relay will disable that circuit, but GM has a backup power path to the fuel pump through the oil pressure switch. Once the engine starts and develops oil pressure, one side of that switch closes and provides an alternative path for power to the fuel pump should the relay fail. The only other route is to disconnect the wiring right at the fuel pump connector itself, and I am not sure if that can be accessed without dropping the fuel tank.
Again, I am not sure how the LPG installation was made, but we had some Dae Woo forklifts at work what were solely propane powered. The fuel lock ( solenoid that turns on and off the propane) was powered 2 ways. First directly off the starter to turn on fuel during cranking, then a oil pressure powered switch to keep the propane flowing as the engine was running. They may have tied into that circuit on your van; it is a gray coloured wire.
The forklifts also had propane filters in the circuit, not positive but I seem to think they were on the low pressure circuit( been over 10 years since I worked on one). They were prone to fouling up and getting blocked, causing problems
Jeff

[Virgis007]

Hi Jeffrv, and anybody else reading this.

So a quick update. Did the spark plug change. Managed to do it in about 20 mins. Good that I'm a skinny guy, so I could just lay on the engine for the rear plugs, but still on untightening the No 6 spark plug hand slipped and got some skin ripped off my small finger, but just about one or two milimeters so no bad at all. The old spark plugs looked real bad, but after the change it didn't feel any better or worse at all on the engine work. When the engine is working it kinda feels like some cylinders ain't working sometimes, and it looked like it on some sparks. One or two were black, and others were in between sand and cappucino color.
So my opinion now is the problems might be seperate or some or all together:
Low compresion in some cylinders;
Bad working (big flow) fuel injectors;
Burnt out valves, or no gap between the camshafts;
CAT stuck with coal, so this gives hard flow out for exhaust gases;
Worn piston rings maybe (but there is no blue smoke or any other suspicious smoke, BUT there is a smell of a non burned fuel, this might not be a cause of the rings);
Other yet unknown stuff smth like bad PCU work, something with wires etc etc magic etc...

About LPG. It would be interesting to make the engine working on it, to see if there is difference in performance. This could make my quess list on what's wrong shorter. I'll try to find the fuel pump wiring, and make the lpg work manual. I'll take the plus from fuel pump, and separate it with a swich 1 - 0 - 2. The 1 will be for petrol (plus goes to fuel pump), 0 plus goes nowhere, and 2 plus goes to the propane opening valves. The lpg system is simple here, it just has the tank, the tubes that goes to the reductor, a valve on the reductor, and a valve before the reductor and after tank with a filter. The reductor it self is fully manual without any electricy except the valve, that opens or closes and that's it here. After the reductor goes a hose straight to the big hose before the throttle flap ( the hose has a screw to calibrate the flow of propane (more or less)). Before the throttle flap there is an aluminium thing round with small holes, where the gas gets mixed with air, and the throttle flap just moves as usual to inlet more or less mixture to the engine and that's it. Newer versions of propane systems have even separate injectors that are drilled and screwed in the intake manifold just before the inlets in cylinder heads, and they have computers for riching or leaning the mixtures and so on. But my sistem is the older one - simplyer. And yep Jeff, I' found that out, by taking out the fuse and cranking the engine while changing the plugs - there was no spark.