EFI Problems Problems Problems tps

[sp71eb]

Well as the title says I am having some odd efi problems. I only have 25 miles on the truck so far. I have done a few KOER KOEO test and the only codes that are not emission related are 12 13 Koer. I am getting 85 44 33 but these are emission codes as far as I understand. I had the truck idling nicely and running relatively well, but under hard acceleration it pops and backfires with a loss of power. Its very odd that the truck runs great until the throttle is mashed, it will come up to full throttle and run great if it isn't mashed. I have...

rechecked timing

The coil, map sensor, act, ect, o2 sensors, plugs and wires are all new.

I replaced the iac and tps with no change.

I unhooked the maf while the engine was running and it wants to die.

When I first installed the iac the engine would die when unhooked but not it will stay running as long as it was unhooked after the engine was started. It seems like the iac is working but not keeping up and controlling well.

I have checked and rechecked for vacuum leaks and replaced all of the crappy rubber caps.

I tried to use the idle screw to lower the idle slightly but have caused the engine to lope badly so I had to screw it back in.

I checked the voltage of the tps and it is at .98 but one odd thing is that if I move the throttle it will go up to around 1.6 and then show open past around 3/4 throttle. This happens with both the new and old tps. This is very odd to me.

I also unhooked the o2 sensor harness and seemed to notice no difference other than a slightly higher idle.

Open to any suggestions or past experiences.

 

[Viperwolf1]

Something isn't right with the way the TPS is installed. You might have it on the wrong side of the blade. Also make sure you have the left O2 sensor on the driver side and the right on the passenger side. You can disconnect one and run codes to see if it tells you which one is disconnected.

 

[sp71eb]

Well elimated the tps issue. I was a dumbass and had my voltmeter set to 2v max. Changed it to 20v max and it does a full sweep up to 4.1v. Now I just have to keep digging and find what the issue is. I tried to do a cyc balance the other day and the code came up with 77(this is from memory) this is wot not detected. Am I not initating the cyc banance test correctly?

 

[00gyrhed]

Sounds like it acts just like a carb with a bad accelerator pump. This may not be the whole issue but its an easy check. The vacuum line of the fuel regulatior is meant to richen the fuel to the cylinders when you suddenly depress the throttle. If it isnt hooked to the right port (basically right behind the throttle plates) It will not perform this function.

I really dont know how much difference this makes since a lot of people run them without the vacuum connection.

 

[ransil]

Dont thing this will fix you problem, but you need to set the throttle screw to idle with the IAC disconnected, get it set to 600-700 rpm.

What is your timing set at?

what is you fuel pressure at idle and when its popping?? may need to tape a fuel pressure gauge to the windshield

 

[sp71eb]

I need to get a tach on it to set the rpm w/o the iac hooked up. Timing was at 12 degrees but I set it to 10 and it doesn't run as well. The truck has a b303 cam. I have an lines to the fuel rail so I don't have the scrader valve anymore. I will have to order a an with a fitting to hook up a fuel pressure gauge. Thats next on my list. I was also thinking about replacing the tfi, but it looks like a complete dizzy is only about 30 bucks more. Might eliminate two birds by just getting a new dizzy.

 

[sp71eb]

Had some free time today so I ran another self test. KOER gets 94, 44, 33 KOEO gets 85, 12, 93, 35. I was able to run a balance test and it came up with 99. The truck really feels like its fighting to contorl the idle speed and the idle surges. I have been unhooking varous sensors to check if the comp knows they are there. I unhooked the vss and the truck didn't run any differnt or throw a code. I am gong to unhook one of the o2 sensors as viperwolf suggested next.

 

[ransil]

other things

shitty ground
air washing over intake
MAF dirty or wrong
check your firing order

do you have a vacuum line connected to the Baro sensor ?

 

[sp71eb]

I'm mass air no vac to the map. I think I may have found the culpurt. I pulled the salt and pepper connectors and ran an ohm meter to my iac and it isn't showing full contunuity to either connector. I am going to pull my upr intake and check out the engine harness tonight. I'm ready to bomb around in the snow damnit and these gremlins are not helping that!

The all of my grounds seem pretty solid
I have a 70mm maf and I swaped it with a 55 and no change.
The engine is running to strong to have a firing order problem in my opnion

other things

shitty ground
air washing over intake
MAF dirty or wrong
check your firing order

do you have a vacuum line connected to the Baro sensor ?

 

[garberz]

Try more advance, 15-17* initial. Both of my buddies running 5.0's seem to need that much. Both of them have E-303 cams. Both Bronco's run very strong, but of idle, they both struggle. Stalling from park to reverse, or drive. Too much cam, not enough stall speed on the TC. They both had dyno tunes done. It helped a bit, but neither of them behave as good as a stock cammed motor.

 

[Ourobos]

Those salt and pepper shakers are know gremlins. Put some good contact enhancer between them. Also you should set your idle screw with IAC disconnected as mentioned, then plug it back in. TPS should sweep to right at 5v, that 4.1v has me wondering too.

Lastly, did you set your timing with the spout plug disconnected? If not your timing is 16 degrees too low.

 

[sp71eb]

Yeah I had thought about deleting the s/p connectors but ended up keeping them. I did clean and dielectric grease the connectors. Yes I disconnected the spout connector and also confirmed the comp is adjusting timing with the spout connected.

Those salt and pepper shakers are know gremlins. Put some good contact enhancer between them. Also you should set your idle screw with IAC disconnected as mentioned, then plug it back in. TPS should sweep to right at 5v, that 4.1v has me wondering too.

Lastly, did you set your timing with the spout plug disconnected? If not your timing is 16 degrees too low.

 

[sp71eb]

Well checked all of the wire junctions and on the engine harness and they are all good and without problem. I then realized that I wasn't checking the correct connector for the iac on the harness. Turns out I was checking the water temp sensor and it was showing resistance to the sig return. Well at least I can eliminate the engine harness from being the problem. Tomorrow I will double check all of my grounds and keep digging. I also forgot to mention that I unhooked the right side(pass) 02 sensor and threw the code for R bank O2 lean code 41 so I would say the 02 sensors are hooked up correct left and right.

 

[Sporto]

How do you have your return line routed? I had a similar issue, with my EFI setup until I rerouted the return line away from the exhaust pipe and muffler. It seems the heat was causing back pressure in my return line and thus creating a condition at the rail. Once I rerouted it, I never had that popping or stalling again.

Just something to consider...

Rich

 

[Viperwolf1]

Had some free time today so I ran another self test. KOER gets 94, 44, 33 KOEO gets 85, 12, 93, 35. I was able to run a balance test and it came up with 99. The truck really feels like its fighting to contorl the idle speed and the idle surges. I have been unhooking varous sensors to check if the comp knows they are there. I unhooked the vss and the truck didn't run any differnt or throw a code. I am gong to unhook one of the o2 sensors as viperwolf suggested next.

The codes that need attention are 12 and 93. 12 says something is not right with TPS or IAC. I would reset the base idle and go from there. 93 is odd because there were no electronic transmissions used during the salt/pepper harness years. What ECM are you using?

 

[sp71eb]

Its an a9L

The codes that need attention are 12 and 93. 12 says something is not right with TPS or IAC. I would reset the base idle and go from there. 93 is odd because there were no electronic transmissions used during the salt/pepper harness years. What ECM are you using?

 

[av bronco]

do you have good fuel pressure when running?

 

[70_Steve]

Timing was at 12 degrees but I set it to 10 and it doesn't run as well.

And does the timing jump up to ~20° when you reinstall the SPOUT connector? CAn you see it advancing as you blip the throttle?

 

[doghows72]

This might be out in left field, but mine would do the same thing. Normal acceleration was fine idle was fine but hard acceleration it would cough and sputter and not go over 60 mph.
Mine turned out to be the wrong VSS. Swapped out for the correct 8 pulse unit and it solved my problem.

 

[EFI Guy]

The 93 code can also be an IAC fault on some PCM's.

I'm leaning towards more of a TPS problem as well. Something is not set right or not wired correctly. The symptoms you describe relate more to transient fueling, which is heavily dependent on proper TPS operation.

I usually advise against ever touching the throttle blade screw, but in your case I'd do the basic idle reset procedure that is posted all over the web.