Really need your help (stumble when throttle is applied)

[85xcab]

Did you get it fixed?

[Wermz84]

Ya Mini, whats the word.  hopefully youve been on it all day and you have some good news for us.   

[93tonkatoy]

Hey Mini, let us know. I'm gonna go out and play with mine and see what i can do to get it to act like yours. will post up if i figure something out. I know mine has acted like that before, but for the life of me can't remember what caused it. Get back to ya in a little bit.



I know mine has done this before, but I don't know. when mine starts spitting and bogging down like that ( not as bad ) if I change the dist cap, rotor button, and plugs, it usually smoothes right out. But since you said it ran fine for a while, then acted up again, I would suspect a bad connection somewhere (loose plug, corrosion...)



Why didn't i remember this sooner? After Ivan (the hurricaine) a lot of the gas stations around here were getting contaminated gas for some reason. It was making the fuel gel into something like a cross between molasses and baby snot. It would clog the fuel filter, pump screen, and the injectors. Fuel injector cleaner, fuel stabilizer, or, for cheaper, 1 pint/10gal of rubbing alcohol would help to break this up in the tank, but you would have to change your fuel filter 2 - 3 times. Or, change the filter and drain the gas tank. This is what happened to mine and also my dad's van (he took his to the shop and found out that it was a common problem at that time. I did mine at home.) Sometimes, if the vehicle sat for a while, it would run better until it picked up enough more of the gunk to plug up the filter or pump screen. Any sediment in the tank can cause it to do the same.

I know, more crap to check!! Keep us posted.

[Willy Mammoth]

Possibly, I haven't given up yet, ECU is least likely.

Just for the hell of it have you opened it up to inspect for hot spots?


edit, I just watched the video on the first post and it is not getting fuel.

Have you checked your fuel pressure or changed the fuel filter?

edit,edit after watching the last video, that is a lean backfire.  Take the fuel hose off the engine and get a pressure gauge on it. If it don't have at least 20 - 30 psi of pressure your pump or filter is a problem. Also do a flow check. Take a beer bottle and put the hose in it and turn the key on. See how fast the fuel comes out and how much. It should fill the bottle in less than 30 sec.

Make sure your air flow meeter plug is clean and no corrosion. That would cause it to run funny .

The tps only tells the ecu the throttle is closed or open. The afm tells the ecu how much air is going into the engine so it can adjust how long to open the injectors for.

Have you had the cover off the afm? you can use a pocket screwdriver to dig the silicone out from around the edge and carfully lift it off. There is a wiper arm under there that should move as more air goes into the engine. If you were to help it while revving the engine and find it makes the engine rev better you may have an air leak between the throttle valve and afm. Or there is a dirty elec connection somewhere.

I would first suspect the fuel pressure.

[MiniSimp]

Fuel pressure:

Disco'd the fuel line before the filter, 18oz in 15 seconds.
Disco'd the fuel line after the filter, 18oz in 15 seconds.

Moving on to testing the ECU

Duffil has added himself to the list of people who have worked on this and are now scratching their heads.

[MiniSimp]

Duffil has gone, and all remains the same.
Can't say he didn't rack his brain though.
Thanks again for taking a look.

TallChevy350, I'll be coming to see you for that ECU, mine tested fine, but better to make sur.e

[Tallchevy]

I hurt my back so I won't be at work until Thursday but your more than welcome to come by my house & get it. I'll send you a PM with my address. Also I'll get the AFM out so you can try that too 

[Duffil]

yeah...apparently my just touching it didn't work this time. 
So. We sort of got it to start better by swapping/cleaning the cold start injector, and verified voltage to said unit.  The ECU appeared to test out good, except for one circuit which seemed to indicate the TPS not properly adjusted.?? Kyle can post the voltage readings if needed...
I checked fuel flow before the filter and then after the filter, results the same, as previously posted.  I will add I didn't have a gauge to check actual pressure.
I noticed the 3 wires that cross the engine to the ignitor had a mystery lump, and upon inspection found green death and some connectors.  Somebody doesn't have a soldering iron, so I went the next best route: clip off the corroded wires, and replace with new crimp-on connectors
I think that was after it developed a new code:6.(RPM signal--no signal from dist. after engine has been cranked OR signal less than 1k but engine RPM more than 1k...ignitor circuit, dist. circuit, ECU[or somethin like that]) this code went away after my new hack job on the wiring.

I drank a beer.

we swapped the "known good" AFM for giggles, and there was now an AFM code...put the original unit back on.
Plugs and wires were changed first thing this morning.

Did I leave anything out?

[*** YELLER ***]

Did I leave anything out?

Yea what is the air pressuer in the tires sounds like you guys covered it all except what do you think about bad fuel or somethin like that

[Duffil]

Yea what is the air pressuer in the tires sounds like you guys covered it all except what do you think about bad fuel or somethin like that

Tire pressure is around 18PSI.

The fuel honestly didn't smell that bad, but kyle did say it's like from MCR5.  I think a good start would be to add a bottle or two to Lucas Octane Booster(it has injector cleaner in it as well)  I think he *could* have a clogged injector, but I kinda lean away from that. I also don't think that bad fuel could cause what it is doing, unless the lack of octane is causing it to  burn too slowly...   What I really need is a way to see what the plugs are doing when it cuts out(to further isolate fuel or electrical), and I might pick up an inline spark tester this week. I really hate working on EFI though.

[*** YELLER ***]

Well as much as you hate it we sure thank you for it BUD   










   

[85xcab]

Mine did some strange things when the igniter went bad, cutting out and stumbling. Maybe the loose connections going to the igniter have caused high resistance and amperage issues damaging the igniter.  I must admit it sounds like it is running lean in the video.
I like to use a timing light to check and monitor ignition problems. Just don't run it to long with out letting it cool down a while.

[Willy Mammoth]

Get a gauge to check the pressure. When it cranks it does not start right away. This could be from lack of pressure or the fuel has drained back to the tank and needs to be pumped back up to the engine and be presurized before it will start. If it does not have good pressure it will starve for fuel and pop in the intake.

I would check fuel pressure with a Tee in the line next. If it is good you can rule it out as a problem.

Also there may be a vacuum pressure regulator that is not restricting the return back to the tank to jack the pressure in the system. If you find the return line you can pinch it off with a pair of needle nose vicegrips. This will cause the pressure to go to it's highest possible pressure.

[Duffil]

Get a gauge to check the pressure. When it cranks it does not start right away. This could be from lack of pressure or the fuel has drained back to the tank and needs to be pumped back up to the engine and be presurized before it will start. If it does not have good pressure it will starve for fuel and pop in the intake.

I would check fuel pressure with a Tee in the line next. If it is good you can rule it out as a problem.

Also there may be a vacuum pressure regulator that is not restricting the return back to the tank to jack the pressure in the system. If you find the return line you can pinch it off with a pair of needle nose vicegrips. This will cause the pressure to go to it's highest possible pressure.

I hadn't thought about that.  I do have a complete fuel injection pressure test set at work that I can snag, but how would I hook it up, mark? the RE has no test port on the fuel rail.

edit: you beat me to it.

[Willy Mammoth]

I hadn't thought about that.  I do have a complete fuel injection pressure test set at work that I can snag, but how would I hook it up, mark? the RE has no test port on the fuel rail.

cut the feed hose going to the engine and put a tee in it so you can run the engine and check pressure at the same time.

[Willy Mammoth]

I have never had any experiance with the Toyota's, but the Nissan injection system is the same design.

[85xcab]

The connection where the metal fuel line goes to rubber is on the right frame rail. Some pressure test kits have threaded tees and adapters you can put in line at connections like that.

[Willy Mammoth]

The fuel pump I had for my turbo motor was capable of 160 psi. That will push a lot of fuel through a small hole.

[MiniSimp]

[Willy Mammoth]

OK WT it ain't that bad you just need to look at it from a differant angle.

[Duffil]

I just got back from the NAPA.  The Mac FIPT that I have should be able to thread onto the fuel filter and tee off right there.

MINI...when is the next work day?

[MiniSimp]

Whenever you want, I'm available from 4:30-11:00pm every day of the week, and both days this weekend.

[highridin4x4]

Hey Mini have you tried a different TPS? Is this the one I sold you ? It may test fine but still have a problem somewhere. Do all of the specs still read what the FSM says? It could even be a bad conection between the TPS and ECU. If you can trace the wires from TPS harness back to the ECU and then run the TPS test there to check the wiring and the conection at the TPS. If you find it to be bad let me know and you can have your cash back.

Scott

[MiniSimp]

Ok, so to update on the progress (and lack of) so far:

Ok, so engine is throwing code 11:
Short circuit is check connector terminal T with the air conditioning switch ON or throttle switch (IDL) point OFF - defective air conditioner switch. Throttle Position Sensor (TPS) circuit, Throttle Position Sensor (TPS) or Electronic Control Unit (ECU) No longer throws this code.

Engine threw code 2 and 6 No longer throws this code

Will not idle below 1300 RPM's After setting timing, Idle is good.

When light throttle is applied it will go to 5K RPM's Actually 3100RPMs is the highest I can get it to go.

When middle/full throttle is applied engine RPM's drop and engine sputters down to 500 RPM's and dies

TPS sensor (2nd one) is good and adjusted

Timing is set to 5*B

Idle is set to 765

There is no air leak from the air box to the throttle body. (air tube is currently wraped in Duct tape.

The AFM tested good with a meter. (AFM has not been modified)

Air box flap moves smooth

Throttle body is clean.

Fuel flow is good before and after the fuel filter (fills 18oz in 15 seconds)

Cold Start injector was replaced with a used one and now works. (fixing the hard start problem)

The ECU tested fine with a meter (except brake switch signal) picking up ECU to swap, just in case.

Spark plugs, wires, dist cap, air filter, O2 sensor are all new.

Igniter tested good with a meter.

There is a light backfire in the intake.

The exhaust is not clogged.

All ground wires are connected.

Tire pressure is 17lbs.

Video with audio:

[Wermz84]

   

[93tonkatoy]

Hey Mini, have you isolated the EGR system? If you pull the two bolts at the rear of the intake plenum and block the port (I used a penny set in the gasket:if you have to take it back out, I would use a nickel.) It sounds a little like maybe the EGR valve may be stuck open causing a "backfeed" into the intake. Less oxygen, no fire. When you open the throttle, more exhaust goes into the EGR back to the intake, less oxygen. Let off the throttle,and produce less exhaust to recirculate. Worth a try?

You are running a cat. conv. aren't you?

[MiniSimp]

Hey Mini, have you isolated the EGR system? If you pull the two bolts at the rear of the intake plenum and block the port (I used a penny set in the gasket:if you have to take it back out, I would use a nickel.) It sounds a little like maybe the EGR valve may be stuck open causing a "backfeed" into the intake. Less oxygen, no fire. When you open the throttle, more exhaust goes into the EGR back to the intake, less oxygen. Let off the throttle,and produce less exhaust to recirculate. Worth a try?

I'm pretty sure Duffil tested that...

You are running a cat. conv. aren't you?

What's a cat? Is that one of those things other people need when they have to smog?

[93tonkatoy]

some of us still live in lower population areas and don't need those.

[Duffil]

Yes, I checked the EGR system, and it seems to be functioning correctly.

[85xcab]

Have you had time to check the fuel pressure yet?