EFI setup erratic behavior under load

[lonicus]

I got to drive the Bronco on the street for the first time yesterday! So yay! But of course, there are always issues.

When I accelerate hard the engine will start popping out the exhaust, I figgured that I have to adjust the timing a bit, then realized that when I get to about 3000-3200 RPM some really wierd stuff starts happening. The Tach goes nuts and starts jumping all around and the engine starts to loose power. If I back off the RPM's it goes back to normal and I get power back.

Using an A9L Computer /w RJM harness.

Im thinking at the moment it must be electrical - possibly the distributer/TFI? I didnt have time to try to pull codes or check timing - will do that tonight.

On a seperate note: on this setup isn't the check engine light supposed to come on when the key is in but engine isnt running? or during cranking? It's not on, but I'm wondering if it's not working.

 

[NYLES]

Too much timing!

 

[lonicus]

Too much timing!

Not timing - re-checked the timing and everything is fine. It stopped doing the popping under load, but the tach still freaks out at around 3k.

Not throwing any codes

 

[NYLES]

you get a running test? reason I ask is I had a bad iab I replaced today, first time it ran a running test and gave codes

 

[jw0747]

did you pull the spout connector when timing checked? is it now just the tach acting up or the engine too?

 

[Viperwolf1]

The tach does make it sound like an ignition problem. Might try it with the tach disconnected.

Where is the purple wire connected on the starter solenoid?
What TFI module are you using (color)?

 

[ransil]

check fuel pressure under load..
TFI module bad, and you are running in limp mode.
Make sure pin 3 & 4 on the TFI are wired correctly one should be 12 volts start only the other 12 volts run only

 

[Steve83]

Yes, the CEL should prove-out before the engine runs. What tach are you using? The EEC doesn't directly affect the ignition system; it only sends an advance signal (SPOUT) to the ICM. Are the plug wires routed correctly?

 

[marty]

i would check that you have the right firing order and maybe try another coil. i have seen bad coils cause this problem. x2 on the tach lead disconnect that first and make sure you don't have a bad tach.

 

[lonicus]

;DThanks for the advice guys, I solved the problem, so if anyone comes across this thread they can see what the resolution was:

The CEL light I had was bad. Just a bad bulb, replaced it and it works as it should.

#1: I forgot to plug in the Spout connector after setting timing. That I think was the cause of the exhaust popping. However the power loss and erratic tach signal still showed up at 3200 RPM.

I ended up deciding to go for the most likely culprit - the dizzy. The Tach has be working fine prior to the swap, and nothing would lead me to think it was causing the problems alone. The Dizzy I grabbed from a pick-a-part and who knows what the condition was. I am not an Electrical Engineer, but my knowlage of circuits lead be to beleive that the PIP signal I was getting was not clean. Not having the equipment to scope a PWM signal, I went to Kragen and bought a new Dizzy last night.

All problems resolved.

I still cant be sure if it was the PIP or something in the TFI - since both got replaced. But the result is a LOT more power, and no weird bechavior. Drove it to work today, not problems whatsoever

 

[lonicus]

Well... Im still having issues

The problems related to 3200 RPM are still totaly resolved by the new dizzy, but the popping is still there. It's not as bad as original - but I'm a bit miffed on what the culprit could be.

The reason being: it only occurs AFTER the engine gets up to temp and the CPU goes from closed loop to open loop mode. I'm still not getting any codes thrown, so it would appear? that all the sensors are working properly.

The engine now will only pop at near WOT when under heavy load. Also, it seems to only do it when the engine is revving quickly. If is say, put the truck in 4th gear while going 10mph and floor it, no problems. But if I hit WOT in 2nd at 10mph it will pop, I can feel a slight loss of power as well. If I back off the throttle a bit it will settle out and drive fine.

Again, since the problem shows only after it goes to open loop, I figgure it has to be a sensory issue, just dont know where? Overall the engine seems to drive better when at temp and the only hint of problems is the popping.

...and the stupid serp belt keeps falling off

 

[Viperwolf1]

No codes as in nothing flashes or no codes as in you see the codes you expect to see?

Ignition and fuel system problems won't throw codes. When they start affecting O2 sensor output you'll get codes.

 

[lonicus]

No codes as in nothing flashes or no codes as in you see the codes you expect to see?

Ignition and fuel system problems won't throw codes. When they start affecting O2 sensor output you'll get codes.

Sorry, should have clarified: I'm not getting any unexpected codes. (get the sandard missing EGR, no VSS input - dont have a VSS attached)

I would have thought that it could be fuel (Though im running 2 fuel pumps that are brand new) and still need to check the pressure. But since I do not get the problem when the engine is in closed loop I would doubt that fuel delivery is an issue, considering cold engines need more fuel then warm ones.

 

[lonicus]

Ok, new info; hopefully someone will have a clue:
Before we get into the codes, I am using a code reader, so no these are not because I can't count.
Ran KOER and cylinder balance tests today: Get the following "important" codes:
28: EDIS or DIS fault <--- what?
88: cooling fan circuit fault <---- Bah-wah?
66: MAF went below voltage <---- hey! a code that makes sense!
18: SPOUT disconnected (except it's not, and this dosent always trigger)

And then on the cylinder balance - it dosen't like #2.
So I ran a compression test - passed that with flying colors, and checked for spark - got that. So I suppose it's possible that the injector is not working properly.

Another odd thing - code 18 and 66 are hard faults which should trigger the CEL, (yes it does work now) but I am not showing anything.

SO... I am more confused than ever before.

Oh - one more thing: after plugging in the SPOUT after re-setting the base timing, it's moving my idle timing up to about 20. That seems a bit excessive - right? the Dizzy and module are brand-new out of the box - so I would doubt that they are faulty.

 

[ransil]

swap # 2 injector to somewhere else and see if the code follows.

Make sure pin 3 & 4 on the TFI are wired correctly one should be 12 volts start only the other 12 volts run only

 

[Steve83]

EDIS = Electronic Distributorless Ignition System: one module that runs several coil packs
DI = Distributor Ignition (System): solid-state with electronic advance

 

[lonicus]

EDIS = Electronic Distributorless Ignition System: one module that runs several coil packs
DI = Distributor Ignition (System): solid-state with electronic advance

So the code 18 and 28 are related then, probably.

I read up a bit on the code reader maual, the computer advances timing on the engine by 20* for 2 min for you to check to ensure timing advance is operational. So that tells me that the SPOUT is, in fact, working as intended.

So, why the code?

I tried retarding the timing a few degrees last night and ran it around a bit. Made the popping worse. So perhaps I need to be running more advance. I will test that out today.

Unfortunatly I have to put the tune-up on the shelf here for a few days (weeks?) because the damn AC compressor failed. Have to send it into Vintage Air and pray for them to warrany it.

 

[Steve83]

Remember that codes can stay in memory for as long as 100 key-on cycles (depending on the EEC), so it's important to know WHEN the code was set. Not all codes turn on the CEL, so you won't necessarily notice it. Now that you've recorded the codes, clear them (by ending the flash test early - not by disconnecting the battery) and recheck every few drives to find out how quickly they come back. That SPOUT code might have set when you were checking the timing.

As convenient as they may be, I've never had much faith in EEC-IV code readers - I prefer the paperclip for its reliability. This caption contains a lot of info about codes, and contains a link with even more...