2.3 Backfire out intake and no spark

[Shumatesoldier6]

So I was having issues with my 1990 Ranger 2.3 two-wheel drive. I got so tired of dealing with it I sent it to a shop, the shop had it for 5 weeks and only worked on it for 2 hours. I got tired of waiting on them so I went and picked it up and I have it back now. The only thing that they did in the two hours that they worked on it was replace the timing belt, and placed a crankshaft position sensor, and set the timing. It is still doing the same thing that it was doing before. I still have a backfire out of the intake and now it has no spark. Before I took it to the shop it had Spark and only had the backfire out of the intake. I went out and bought a new mass air flow sensor and that didn't change anything. I also got an ignition control module and 4 new injectors that I haven't had time to install yet. What can actually cause a backfire out the intake? I know the timing is right, I'm beginning to think that the ECM is bad and causing all these problems.

 

[RonD]

1990 2.3l will only have spark on the exhaust spark plugs while cranking engine over, none on intake side until engine starts
1995 and up had spark on both sides while cranking

Back fire out the intake would be intake valve still open when there was enough gasoline vapor for spark to ignite
Double check exhaust side coils pack firing order

Only way to be sure timing and valves are correct is to do a compression test, take that off the table first thing.

2.3l should be running 160psi compression
Pull out 1 spark plug in each cylinder FIRST and then test each cylinder one at a time
That will give you best crank speed for test, also prop throttle open all the way, that turns off fuel injectors and gives best air flow for test

If you have a bad valve, "tuliped" intake valve or a rocker has shifted, not letting intake valve close all the way, compression test will tell you
Also tells you if overall crank cam timing is correct, i.e. 160psi in all 4 cylinders
If they are all 130psi then cam is one tooth off

 

[Shumatesoldier6]

So if I have compression 130 psi or more a valve is bad or not closing thats what your saying RonD?

 

[RonD]

No, I am saying test compression in all 4 cylinders and the results will tell you the next step

 

[rusty ol ranger]

With compression uniformity among cylinders is actually more important then individual PSI readings.

Unless there all super low then its time for a rebuild.

 

[RonD]

Yes ^^^^ +1

But with the 2.3l Lima and timing belt, especially since it was just changed, if all cylinders are equally low then installer of belt may have installed it 1 tooth off on the cam.

 

[Shumatesoldier6]

Ok Thanks im gonna test compression asap.

 

[Shumatesoldier6]

So im positive tbe shopthat worked on my truck set the timing wrong. It was set at TDC. Timing should be set at 10 BTDC? Still has a popping out intake when i try to start it and weak spark if it sparks at all.

 

[RonD]

Spark timing is at 8-14deg Before TDC, and you don't have a distributor in a 1990 2.3l, so moot point

Cam/crank timing is set at # 1 TDC

 

[Shumatesoldier6]

I also just replaced the injectors and at wide open throttle the injectors are not shutting down. Is this a computer issue? I have replaced all the sensors and electrical components but the ecm.

 

[RonD]

Make sure you are getting WOT using gas pedal
Get a stick and use it against the seat to press gas pedal down to the floor
Then go to engine and see if you can manually open the throttle more, if so then you need Throttle Cable Mod

Computer shuts of fuel injectors(Clear Flooded Engine) when it sees 0 RPMs, and the Throttle Position sensor(TPS) is showing above 4.5volts
TPS gets 5volts from computer
At throttle closed computer should see under 1 volt, .69 to .99 is spec, back from TPS
At WOT computer should see 4.50 to 4.99 volts, from TPS

 

[Shumatesoldier6]

Thanks RonD ill try that. I was holding it wide open by hand and taking the terminal on and off with the key on

 

[RonD]

Thanks RonD ill try that. I was holding it wide open by hand and taking the terminal on and off with the key on

???