Question about Chevy 2.2L S10 (tools)

[Fishey]

So I got a 1995 Chevy 2.2L S10 in my shop that isn't running correctly and I am by no means a chevy expert. It has an OBD2 port but none of my scanners will communicate with it.

When I first got it it would not run but after messing with it a bit I got it to run (badly but running).

It has spark and according to my testing its decently strong spark. I also checked timing (I marked spot in crank at TDC) and used a timing light to see if it was atleast in the ballpark and it seems to be around 10degree BTDC that its igniting the #1 cylinder. So timing and ingition seem to be reasonable so I did a compression test and it did 180psi on all 4 cylinders. So now I am pretty suspicious of fuel mixture and given my lack of experience with the GM product I came to a few conclusions on what controls mixture.

1. MAP Sensor (Working correctly I did voltage vs vac test)
2. Engine Intake Temp Sensor (Working correctly res vs temp test)
3. Engine temp sensor (gauge and ECU) and also getting good results from testing. However, I did shotgun a part at it since it was only $14.
4. 02 sensor but clearly not going to have any effect on startup.
5. I also checked voltage output from the throttle position sensor and it seems to be alright.

So, I cleaned the throttle body and checked the idle motor and all ports are clean and motor is working what seems to be correctly.

The truck will idle decently with a few stumbles but will not take throttle.

However, if I open a vac leak the truck runs way better and will even take a bit of throttle. Also, if I unplug the map sensor from the engine and pull vac on it to lean out the mixture the truck runs pretty damn good. So I tested vac in the manifold and its a lousy 5inches of vac. So now I am thinking vac leak at the intake manifold.

My real question is does any scanner work with this 95 truck?

 

[Jawn]

How's the fuel pressure?

Being a 95, that shouldn't be OBD2. I thought that was 96-up.

edit: You may be right on the vac leak... try some ether or something around the manifold?

 

[redline380]

the connector is probably obd2 style, but it needs an obd1 scanner. that would be my guess. but on second thought i know even the cheap obd2 scanners come with cords (or at least use to) for obd1 hookups. you may need an odb1 cord since im sure the wires are different

 

[LEVE]

All you need is a paper clip, read this:

Read GM Diagnostic OBDI codes for free

 

[Fireball027]

All you need is a paper clip, read this:

Read GM Diagnostic OBDI codes for free

That works fine to get any codes, but it provides no data.

 

[pipsters]

If it has an OBD2 connector it should pull the data. I have a 95 Volvo with OBD1 and OBD2 connectors (separate) and they both work.

 

[Fishey]

How's the fuel pressure?

Being a 95, that shouldn't be OBD2. I thought that was 96-up.

edit: You may be right on the vac leak... try some ether or something around the manifold?

Fuel presure is at 43 and from what I have found that is in spec

Also, I just checked on the Vac leak.. no dice..

Oh, the OBD2 (16 pin) port all the pin tricks I know involve the 12pin port. The 16pin connector certainly doesn't work but does give power. Also, I have a spare ECU for the car and it does the same thing simply will not communicate.

 

[tribbles]

The jumper trick might or might not work on that year. My '95 Caprice has an OBD1 ECU with an OBD2 port, and the jumper trick does NOT work on it. Unfortunately that's what all the Vato Zones around here do with OBD1.

 

[Thunderbisciut]

I had one of those trucks at one point, and that damn connector threw me off too. A lot of people refer to them as obd1.5. They're a step up from obdi, but not compatible with obdii. You'll need to find a scanner that specifically states that it is compatible with them.

I think I had to use pins 5 and 6 with an analog meter to pull a code off of it.

 

[bobemmerich]

Yep. 95/96 Gm's. You need a connector to go from OBD2 to OBD1. I had the same issue on my 95 GMC. The paperclip trick probably won't work.

 

[Fishey]

Idle control valve should you be able to move it by hand? I can't move it but it does seem to move when plugged in..

 

[otis66]

Have you checked the air filter? Check make sure all of the vac hoses are okay. Take some carb spray and spray around the intake and vac lines. Also fuel could be bad or just a bas TPS.

 

[Big-Foot]

I would do a couple of things:

1) read your voltage output of the TPS with an analog meter rather than a digital one. Slowly ramp up your throttle setting while watching the needle in the meter, they should move together and smoothly with no jumping of the needle. If the needle jumps, your TPS is shot.

2) look for vacuum leaks by using an unlit propane torch. The idle speed will increase immediately when you find the leak.

3) pull the egr valve out and make sure the pintle is clean, then check the condition of the hoses and make sure it's connected to the proper port.

4) check for a bad or disconnected ground. If there is a bad ground to the harness or to the injectors, they will not fire right.

 

[454ragtop]

Check for a plugged converter, disconnect the exhaust at the manifold.
Jim

 

[greasemonkey44]

Check for a plugged converter, disconnect the exhaust at the manifold.
Jim

either that or fuel pressure

 

[wafrederick]

There are early OBDII vehicles,started in 1994.I have seen 1994 Buick Park Avenues this way,have the OBDII plug.The ecu has to programed with the Tech 2 and GM's Tish program even with used ecus.I like GM's computers,can be used over and over again.GM is the only one that does this.

 

[jethro29]

with that vacum reading and your reported symptoms i would suspect a clogged cat.

 

[Jawn]

Check for a plugged converter, disconnect the exhaust at the manifold.
Jim

I think you're onto it.

 

[DesertRatAutomotive]

Sounds like a intake manifold gasket to me. Spray bottle test it.

 

[Vegaman_Dan]

The two most common engine faults on the 2.2L on the S10's are the fuel pump dropping pressure randomly and the O2 sensor going. What throws people off on the O2 sensor is that there are *two* of them. One up on the exhaust manifold, and the other down below at the exhaust pipe (get to from below). It's the second one below that fails more often, but people replace the one they can see without any effect.