SBC 350 TBI: Help w/ Error Troubleshooting (1 Viewer)

[terrx]

Here are those part numbers for fuel filters. They are 3/8" hose barb which is ok for TBI pressures.

Prefilter between tank and pump:
Holley part # 562-3 -- Holley Performance Products Fuel Filter*562-3

Filter, between pump and throttle body:
NAPA part # 3482 -- Part Detail

There are other options for prefilters, but the Holley was the least expensive route I found. Reusable/cleanable filters (many brands) can get expensive. You can order the Holley from Shucks/Kragen/Orielly or Summit/Jegs/Amazon.

My guess is the vacuum is low. The MAP readings in the datalog look too high for idle. Keep in mind the IAC is essentially a vacuum leak. Depending on what you're trying to accomplish with the vacuum gauge defeating the IAC may help isolate other issues. The procedure to set minimum air will tell you how to block it off, IIRC by removing the connector with key on engine off. Here are a few more ideas: Are you using an EGR valve & is it connected to the throttle body & wired in? Also I seem to remember in a previous thread you found some valves were to tight. Are you sure they're adjusted ok now and the compression is good? Is the cam stock?

 

[Elbert]

Is the truck setting trouble codes? If it is...you need to fix that first...before trying to run down the other things. If I were you, I would leave the idle ajustment alone as the IAC and th ECM control idle. TDC at # 1 with base timing at zero degrees... that's fairly easy to set. As I mentioned the TBI engines are very senstitive to the base timing setting...has to be on zero.

Follow the diagnoztics trouble code trees in the shop manual....they are very helpful. You need to get the timeing squared away first... (if your valves are not adjusted right...then that should be first..then timing.

After that you have to run down the trouble codes.

A TBI setup is one of the simpler fuel injection setups... In my view if you're setting codes then you have to solve that first, because screwing with other sensors or changing settings may just add to your issues. You need all the sensors connected and working, that has to happen for the truck to run right at a base level.

 

[nicholastheczar]

Here are those part numbers for fuel filters. They are 3/8" hose barb which is ok for TBI pressures.

Prefilter between tank and pump:
Holley part # 562-3 -- Holley Performance Products Fuel Filter*562-3

Filter, between pump and throttle body:
NAPA part # 3482 -- Part Detail

There are other options for prefilters, but the Holley was the least expensive route I found. Reusable/cleanable filters (many brands) can get expensive. You can order the Holley from Shucks/Kragen/Orielly or Summit/Jegs/Amazon.

My guess is the vacuum is low. The MAP readings in the datalog look too high for idle. Keep in mind the IAC is essentially a vacuum leak. Depending on what you're trying to accomplish with the vacuum gauge defeating the IAC may help isolate other issues. The procedure to set minimum air will tell you how to block it off, IIRC by removing the connector with key on engine off. Here are a few more ideas: Are you using an EGR valve & is it connected to the throttle body & wired in? Also I seem to remember in a previous thread you found some valves were to tight. Are you sure they're adjusted ok now and the compression is good? Is the cam stock?

Thanks for the filter numbers. I have Napa pre and post filters on right now but I'm not sure of the micron rating. I don't have an EGR valve on my motor and the ports on the throttle body are plugged. I had the valves adjustd by a mechanic in town. I have not checked the compression after the valve adjustment. The cam is a RV cam and was a new cam when the motor was rebuilt.

Nick

 

[nicholastheczar]

Is the truck setting trouble codes? If it is...you need to fix that first...before trying to run down the other things. If I were you, I would leave the idle ajustment alone as the IAC and th ECM control idle. TDC at # 1 with base timing at zero degrees... that's fairly easy to set. As I mentioned the TBI engines are very senstitive to the base timing setting...has to be on zero.

Follow the diagnoztics trouble code trees in the shop manual....they are very helpful. You need to get the timeing squared away first... (if your valves are not adjusted right...then that should be first..then timing.

After that you have to run down the trouble codes.

A TBI setup is one of the simpler fuel injection setups... In my view if you're setting codes then you have to solve that first, because screwing with other sensors or changing settings may just add to your issues. You need all the sensors connected and working, that has to happen for the truck to run right at a base level.

I am throwing a error code 33 (MAP high (Manifold Air Pressure)) and a 45 (O2 rich (o2 sensor). I had set my #1 cylinder at TDC when I set the intial timing. My motor doesn't have any timing marks on it so I didn't have anything else to confirm my settings.

I'm going to check my vacuum and see if I can't find a leak.

 

[Elbert]

your engine does not have a timing tab on the timing chain cover? If not then you might as well stop and get a new cover with the timing marks, because you are going to guess if no reference point?

The ECM takes whatever the base timing is...and either advances that or retards that based on engine parameters and conditions. If base timing is off, then the advance or retard is off as well. The TBI ECM is not "smart" in that it would be able to tell if setting was wrong. Its made to work off certain known factors.

I don't know how you can set base timing at 0 degrees without timing reference both on the harmonic balancer and the timing cover. As I recall the TBI engines have timing reference made on to timing chain cover. You might get one of the timing tabs that bolts to the timing chain cover. but I'm not sure that would replciate the same position. I may be confusing the different versions of 5.7 engines regarding the timeing tab made as part of the timing cover but in any case you need a timing reference to align with harmonic balancer mark.

You cannot "eyeball" these settings with fuel injection engines.... Have you replaced MAP and 02 sensors? Do you have VSS sensor connected and all other fuel injection related sensors connected?

Does the TBI enigne only have one 02 sensor? As I recall that's all mine had...

The fomer pickup I had with 5.7 TBI would only run "right" when base timing was 0...anything less or more and it did not run worth a "*$*^)".

 

[nicholastheczar]

your engine does not have a timing tab on the timing chain cover? If not then you might as well stop and get a new cover with the timing marks, because you are going to guess if no reference point?

The ECM takes whatever the base timing is...and either advances that or retards that based on engine parameters and conditions. If base timing is off, then the advance or retard is off as well. The TBI ECM is not "smart" in that it would be able to tell if setting was wrong. Its made to work off certain known factors.

I don't know how you can set base timing at 0 degrees without timing reference both on the harmonic balancer and the timing cover. As I recall the TBI engines have timing reference made on to timing chain cover. You might get one of the timing tabs that bolts to the timing chain cover. but I'm not sure that would replciate the same position. I may be confusing the different versions of 5.7 engines regarding the timeing tab made as part of the timing cover but in any case you need a timing reference to align with harmonic balancer mark.

You cannot "eyeball" these settings with fuel injection engines.... Have you replaced MAP and 02 sensors? Do you have VSS sensor connected and all other fuel injection related sensors connected?

Does the TBI enigne only have one 02 sensor? As I recall that's all mine had...

The fomer pickup I had with 5.7 TBI would only run "right" when base timing was 0...anything less or more and it did not run worth a "*$*^)".

When I was setting my timing, I looked all over my cover for a mark, but could not find one. i have new MAP and O2 sensors. I have one O2 sensor on my passenger side. I have a VSS but it is not installed yet. i just recieved my VSS on Saturday but I haven't hooked it up yet. The more I work on it, the more I think I need to go back to setting my base timing and starting over.

Nick

 

[Downey]

I still think your problem is no VSS. First, I don't think Jags sells a metric sender with Toyota drive tangs?? Second, I would need to know what signal your electronic spedo requires (normally 4 pulses, but many are adjustable). I think you will need a 2 pulse VSS for your engine (I have one left, then I'm out) and possibly a Signal Interface from Dakota Digital to adjust the 2 pulse signal to what ever your spedo requires---then your done!!!!!

 

[nicholastheczar]

I still think your problem is no VSS. First, I don't think Jags sells a metric sender with Toyota drive tangs?? Second, I would need to know what signal your electronic spedo requires (normally 4 pulses, but many are adjustable). I think you will need a 2 pulse VSS for your engine (I have one left, then I'm out) and possibly a Signal Interface from Dakota Digital to adjust the 2 pulse signal to what ever your spedo requires---then your done!!!!!

I bought a 2 pulse VSS from jags that has a metric fitting to mount to the transfer case and standard threads to allow my autometer sender (16 pulse) to attach to the VSS. The tang that came w/ the JTR VSS fits my transfer case and the other end allows the tang from the autometer to fit the VSS. Looks like it will work. When i get home tomorrow, I'm going to hook everything up and see what happens.

Nick

 

[nicholastheczar]

I hooked a vacuum gauge up to my throttle body and with my VERY VERY rough idle I am only pulling 5-10 inches Hg at idle. I know this isn't right. I pulled my plugs (which are brand new) and they are so fouled and black it looks like they are 100 years old.

Nick

 

[Elbert]

rich 02 sensor code ?

 

[nicholastheczar]

rich 02 sensor code ?

Yes, error code 33 (MAP high (Manifold Air Pressure)) and a 45 (O2 rich (o2 sensor)).

I cleaned the plugs and did a compression test for the heck of it. Good compression (avg about 145-150). It is running better now but the idle is still rough. I took the Idle Control Valve out and cleaned it w/ throttle body cleaner and then replaced it. I drove it around this evening and it was driving pretty good and is now idling about 700rpm about 40-50% of the time, the other 50-60% is rough idle and I have to push on the gas to keep the motor running. I still don't have my VSS on yet, that is tomorrows project. Hopefully that will help smooth it out.

Nick

 

[nicholastheczar]

My VSS is on and I replaced my IAC, which I believe may have been a source for a vacuum leak. I no longer have the code 33 but am still having the code 45. My exhaust is partial black smoke when I first fire it up and it runs rough until I get it out of the garage and run it for a bit, then it seems to idle fine (a little bit of a high idle) but it idles. It is better but still running rough and is rich. My BLM #'s were low at around 109 and my O2 sensor numbers high. Any other ideas on how to get my engine to not run so rich?

Nick

 

[hank14]

Nick- can you manually increase the throttle, hold it steady, and get higher vacuum readings? If you rev it up, does the vacuum jups up to 21+, and then back down when you quickly let off the throttle?

After talking to you the other day and now reading this thread, I wonder if Elbert is right and maybe the timing is significantly off. The computer would try to adjust for this but not be able to get it running right. Maybe we can look at it this weekend. I'll ask a mechanic friend if there's another way to locate TDC.

 

[Elbert]

remember you are not talking about static TDC.

I may be using the wrong expression...(disregard my TDC reference) anyway with engine running, you disconnect brown wire, and with timing light connected you set timting to 0 degrees, lock down distributor and then reconnect brown wire. I would disconect battery cable to clear codes after doing this. Once again you cannot eyball this setting. You are going to need a proper timing reference. Take some whiteout or white marker and mark the timing mark on the harmonic balancer so you can see that easy, then set the timeing with the timitng light and appropriate timintgreference. Are you sure that you have no timing tab?

Just my view that this setting cant be guessed at. I spent some time one day getting my former pickup timing right. a little to advanced or retarded...off zero degrees and engine ran like crap.

THe problem with working other issues is that your base timing affects many other things, if its wrong and then the computer jacks it way up or way down, becuase the computer thinks the timting is at zero.

TBI enignes are the simplest fuel injection setup...there are no "smarts" built in....the ECM does not have any clue that base timing in not right. I don't think you can read timing via scan tool on this engine...you can read something like that on the 5.7 vortec but its called crank offset as I recall.

You have to baseline a fuel injected setup because to many things overlap... Get the mechanical portion squared away...ie base timing, then work on other issues following the trouble code diagnositc flow charts in the shop manual. my experience is that if the TBI engine gnererally sets a ocde that points to a sensor...you might as well swap the sensor to start with.

 

[nicholastheczar]

Nick- can you manually increase the throttle, hold it steady, and get higher vacuum readings? If you rev it up, does the vacuum jups up to 21+, and then back down when you quickly let off the throttle?

After talking to you the other day and now reading this thread, I wonder if Elbert is right and maybe the timing is significantly off. The computer would try to adjust for this but not be able to get it running right. Maybe we can look at it this weekend. I'll ask a mechanic friend if there's another way to locate TDC.

remember you are not talking about static TDC.

I may be using the wrong expression...(disregard my TDC reference) anyway with engine running, you disconnect brown wire, and with timing light connected you set timting to 0 degrees, lock down distributor and then reconnect brown wire. I would disconect battery cable to clear codes after doing this. Once again you cannot eyball this setting. You are going to need a proper timing reference. Take some whiteout or white marker and mark the timing mark on the harmonic balancer so you can see that easy, then set the timeing with the timitng light and appropriate timintgreference. Are you sure that you have no timing tab?

Just my view that this setting cant be guessed at. I spent some time one day getting my former pickup timing right. a little to advanced or retarded...off zero degrees and engine ran like crap.

THe problem with working other issues is that your base timing affects many other things, if its wrong and then the computer jacks it way up or way down, becuase the computer thinks the timting is at zero.

TBI enignes are the simplest fuel injection setup...there are no "smarts" built in....the ECM does not have any clue that base timing in not right. I don't think you can read timing via scan tool on this engine...you can read something like that on the 5.7 vortec but its called crank offset as I recall.

You have to baseline a fuel injected setup because to many things overlap... Get the mechanical portion squared away...ie base timing, then work on other issues following the trouble code diagnositc flow charts in the shop manual. my experience is that if the TBI engine gnererally sets a ocde that points to a sensor...you might as well swap the sensor to start with.

I believe both of you guys are right, timing. I do not have a timing tab, I looked for it before I had my water pump and serpentine setup on, nothing. I should have put one on while I had all that junk off. I'm going to the auto parts store today and buying a tab that bolts onto the timing cover. Then I will reset my motor back to TDC by pulling the #1 plug and watching for the piston to come to the top of its stroke. My rotor should be pointing at the #1 cylinder when I do this because of how I set it up the first time (that way I know its not 180* off) and then I'll know I'm at TDC. I'll pick up a timing gun and go from there.

Scott, that is pretty much what is happening and I think it is timing. I'm going to be out of town Thursday - Sunday and will be at work on Sunday, so no wrenching time for me. Maybe if your off Monday or Tuesday we can look at it. Thanks again for letting me borrow the vacuum gauge. If all goes well, I'm going to try to make the LSLC meeting in Dallas this month. Care to join?

Nick

Nick

 

[Elbert]

Nick..

maybe I'm not tracking but I don't see a need to mess with setting static timing at TDC.. With static timing you don't have to be just right. If the truck starts and does not pop and backfire you are in the ballbpark... then you proceed to set "base timing" by disconnecting the brown wire while engine running and set to zero degrees.

Elbert

 

[nicholastheczar]

Nick..

maybe I'm not tracking but I don't see a need to mess with setting static timing at TDC.. With static timing you don't have to be just right. If the truck starts and does not pop and backfire you are in the ballbpark... then you proceed to set "base timing" by disconnecting the brown wire while engine running and set to zero degrees.

Elbert

Ok, I'm following. So if my base timing is good, then I can just get a timing gun and adjust my dizzy cap to adjust my timing? Correct? With the brown wire disconnected.

Nick

 

[Elbert]

Yes, that's what I would do... Get a timing tab, and set the timing at zero with wire disconnected.

 

[nicholastheczar]

Yes, that's what I would do... Get a timing tab, and set the timing at zero with wire disconnected.

But how will I know if my timing is as 0 before i install my new timing tab? Won't I have to make sure I'm at TDC to ensure I'm am at zero? How else can I make sure I'm at 0 with no timing tab?

Nick

 

[Elbert]

If the truck is running fine (reasonably well) you should be in the ballpark. STATIC timing at TDC #1 cylinder is to get your distributer in phase with the camshaft / crankshaft. YOu don't have to hit this mark exaclty but you have to be close for the truck to start. If no popping and sputtering and backfireing through the throttle body you should be close. This setting is just loose to get engine started after rebuild or if the distributor is removed. YOu then proceed to adjust timing as mentioned below.

Assumption you are ok on this (from where I sit)

Get timing tab and then procced to set base timing with wire disconnected.


Dont' get caught up on the TDC reference....remember I stated that I worded my prior response wrong and I mistated the TDC reference.