Might need new engine. Whats the diffs?

[aarcuda]

My 95 PA with the Series II engine took a poop last year and I had the motor rebuilt by a local company in town.

At first it seemed ok but it didnt seem to have the same power as when the original motor was newer. now, it doesnt run very well at all after just 11 months and 15,000 miles.

it lacks vacuum going up hills so the ac vents switch to the windshield. The cruise doesnt hold if you set it going up a hill either.

It also kicks down going up hill from lack of power. And it feels like on the freeway, the pedal needs to be pushed more than normal.

I changed plugs, filters (fuel and air) and no difference.

Did a compression test and the numbers at 4 puffs read around 135 psi (down from 160 from about 7 months ago). If I check the compression max (at like 8 or 9 puffs), it went to about 190 (but after cranking it to check 3 plugs, the max dropped to 160 on all cylinders- even on the ones that originally measured 190).

So i think the motor is not doing so well and Im think of getting a new engine from GM (Part # 89017262).

Does anyone know if the 95 3.8's have the same camshaft as the newer 3.8's (in other words, will it have the same power as the 2004 impalas that I rent when Im on business trips)

Anyone know if the computer needs changing if I decide to dump a new supercharged series III motor in there?

[tman]

A new Series II 3800 will have 205 horse instead of 195.

I'd actually reccommend the SC Series II as opposed to the Series III The series III makes only 10 more horsepower, with the same torque, and is probably much more expensive than the series II

[parkavenuechrome]

no warranty on the motor? The new motor will be nice.. Jasper engines makes a decent 3.8 for around 900 bucks rebiult. they have a 3 year 36000 mile warranty.. But a new one would be nice if your car is in great shape..

[aarcuda]

motor has a 12 month 12,000 mile arranty that expires in November (the 3rd) but I am at 15,000 miles so they will probably say Im outta luck (these kind of places don't like to warranty anything and they will say whatever they can to make the problem your fault and not theirs).

I think I will run it until it is unbearable. a new motor is $2500 on gmpartsdepot which is more than a rebuilt motor (my rebuilt was ~$900) but it is the hassle of pulling and changing.

Anyone know how to prime the oil system with the 3.8 liter?

[parkavenuechrome]

just a thought, maybe you can try to reset the Valve Lash, sometimes with the rebiulds the rocker arms get loose and don't hold the valves open causing the crappy HP and vacuum... is the motor quiet or does it sound knocky?

[aarcuda]

hmmm, good point. the motor sounds fine. not knocky at all. I will check it out. I was also thinking that maybe there might be a vacuum leak (I am hoping for something easy).

I should say that I have this tendency to think all automotive problems are the worst possible breakdown (like bad engine, tranny gone south, wheel bearings shot) then when I get into it I find its something stupidly simple (like needs new plugs, ujoint bad etc). So theres a good chance I dont need a new engine.

I'll check the valves and the intake for leaks this weekend. thanks for the hint.

You (parkavechrome) mentioned in another post, that fuel injectors might be suspect after say 150,000. seeing as my car has 192,000, I was thinking that I should check them as well. Is there any way to do this at home or do I need a special setup. I was thinking of pressureizing thethe rail and applying power to each injector to see the spray pattern but Im not sure what power to apply to the injector (+12v??? or something else). any ideas?

[Jed Rule]

I have used a can of injector cleaner that attaches to the pressure fitting on the fuel rail. You disable the fuel pump and run the engine for 10 minutes on the cleaner.

[parkavenuechrome]

its defiently not +12 volts.. they work on very low signal from the ECM.. if you have 192,000 and there original then there for sure on the way out. if you pull them off and look at them if the tips are burnt or cracked, replace. with 192K they will fail. The only way to test is on a tech machine at the dealer that watches the injectors or weakness or missfire. take them off, crank the motor and watch the spray.. but definetly check the valves. Also you could have bad head gaskets.. presurize the cylinders check for adjacent cylinder pressure.

[Flatrater]

Originally Posted by parkavenuechrome

its defiently not +12 volts.. they work on very low signal from the ECM.. if you have 192,000 and there original then there for sure on the way out. if you pull them off and look at them if the tips are burnt or cracked, replace. with 192K they will fail. The only way to test is on a tech machine at the dealer that watches the injectors or weakness or missfire. take them off, crank the motor and watch the spray.. but definetly check the valves. Also you could have bad head gaskets.. presurize the cylinders check for adjacent cylinder pressure.

And you know for a fact that the injectors aren't pulsed at 12 volts. I beg to differ with you on that.


Also a spray pattern on an injector is a part of a test but that is the last part I would do. A pressure drop test is good to do or a power balance test is even easier. Usually if you have an injector problem you will have a misfire problem. Any car built after 1995 will also give you a check engine light with a stored P0300 misfire code.


There is no time limit or mileage limit on injectors I have seen them fail at 5000 miles up to 250,000 miles. The injectors themselves are reliable/ Its the crud in the gas that kills them.


Bad head gaskets either would leak coolant outside the engine or you would get exhast gases in your radiator. There is a simple test to determine if your headgaskets leak using a chemical that changes color when exposed to exhaust gas.


Instead of wasting your money on throwing parts at the car take it to a good shop pay the one hour diag fee and have them scan the car and see what they find. That 70 dollars is lot cheaper than one injector.

[aarcuda]

I think the diagnosis idea is a ggod plan. with all of the variables that it could be, I could be under the hood for days. Plus, if the motor is going south, better that I have a professional diagnosis to give to the rebuilders than just my own statement.

I just like doing things myself (however, I have used the professionals to diagnose problems before and then completed the repairs myself)

[parkavenuechrome]

I biuld Mustangs, work on saabs, and many GMs.. The injectors are not pulsed on 12V...

[aarcuda]

hmmm, this seems to say that it is a 12v pulsed circuit (at least for the misubishi stealth) through a resistor to limit the current.

http://www.stealth316.com/2-injectortypes.htm

and this,

http://www.megasquirt.info/manual/minj.htm

and this

http://www.cleanairpower.com/files/p...0injectors.pdf

Of course with this resistor in the circuit, the voltage across the injector will be less than 12v. So, if the PCM has this resistor internal to it, the voltage at the injector will be somewhat less than 12v. If I had a scope, I could measure it.

In any event, I made an appointment to take the car in tomorrow. I'll let you all know what the shop finds out.

[parkavenuechrome]

the voltage coming to the injectors is well under 12V.. the entire car is a 12V circuit. If you put 12V to the injectors. there toasted, and as far as life expectance, the injectors will go regardless... Its a mechanical item that opens and closes and with that mileage they are prone to fail and known to as well..

[aarcuda]

its the current that will toast the injectors. a lot of my current research has found that there are high impedance injectors and low impedance injectors. if the inject is low impedance (such as 2.5ohm) then a separate 6 ohm resistor is used to reduce the current to about 1.4 amps max ( 12v/(2.5ohms+6ohms)=1.4amps). this setup drops the voltage at the injector to around 3.5 v (1.4A X 2.5 ohms = 3.5v).

in any event, the injector signal is pulsed so depending on the pulse rate, repetition and duty cycle, the average volateg to the injector is quite small.

I took my car in this morning. I'll let you know what they find. I am now thinking that its not the motor. I seem to have great pickup when I floor it. the car just lacks part throttle ummfph. and the vacuum problem. We'll see what GM has to say about it.

[Flatrater]

Originally Posted by parkavenuechrome

I biuld Mustangs, work on saabs, and many GMs.. The injectors are not pulsed on 12V...

All GM injectors are pulsed at 12 volts look closely at the schematic I am linking to, at the top of the schematic is the fuse for the injectors. If you take a meter to that fuse you can measure it but save your time.

For your info I am a GM master tech working at a Pontiac, GMC and Buick dealership.


LOOK HERE AT THE SCHEMATIC

http://134.39.200.6:9001/servlets/TifToGif?pic=56622