TBI 454 running poor and throwing codes.. CURED!

[KeyBlazer]

Rebuilt my 87 Suburban TBI motor...
Now it starts and runs ok when cold but when it warms up it shows a Check Engine light when driving..
Codes reading are:
13
32
33
44

Can someone suggest how to track down the solutions?
The motor feels good anytime except hot at idle, where it hunts and surges enough to make it jerk forward when stopped in traffic.
When the check engine light comes on you feel the motor hesitate for a second.
Thanks in advance!

 

[RedBrute]

Code 13 is oxygen sensor
Code 32 is EGR related
Code 33 is MAP sensor high
Code 44 is oxygen sensor LEAN

I suspect you have a vacuum leak in the system...
How is the condition of the ignition system EI: plugs wires cap rotor in good shape?
Check all vacuum lines, PCV valve, brake booster vac line, base gasket to TBI.
Also,search this forum for "vacuum leaks" for other ideas.

 

[dyeager535]

There is supposedly a method to the codes, but I've not seen it in the service manual...either start with the highest or lowest code and go from there, I can't recall which.

Code 32 should be a cruise only code, when do they all pop up?

 

[Thunder]

It looks like you have more than one thing wrong.
Wnen you installed your new engine did you hook up all the sensors, componets vaccum lines, correctly?
Code 13 usually indicates a bad or shorted 02 sensor. Is the 02 sensor hooked up?
Both Codes 32 and 33 coming up may be a bad MAP sensor, massive vaccum leak or EGR valve stuck open or not operating.
Code 44 is lean AF mixture which also points to a bad vaccum leak, EGR valve stuck open, bad MAP sensor, bad 02 sensor.
If you have everything hooked up right.To fix i would start with replacing the 02 sensor, check for EGR operation and Vaccum leaks repair as needed.
Clear all trouble codes.
Drive to see how things are working.
Then check trouble codes. see what comes up.

 

[KeyBlazer]

Sorry for the silence... Been crazy busy at work...

Ok, spotted a vac line to the charcoal canister that was off.
Just crawled out from replacing the O2 sensor, and rechecked the tightness of the Throttle Body bolts... they snugged up about half a turn...
Gonna reset the codes but removing battery cables now and will report back in a bit...
Fingers crossed!

 

[KeyBlazer]

Ran it and it has not thrown a code yet... but I have not driven it on the freeway yet... smog has expired now so I am kinda stuck.
It just does not sound happy..
Any clues on looking for the Vac leak?

 

[eagle mark]

This is dangerous but works well, do it outside, no wind. Spray short small bursts of starter fluid to specific spots from about 2-3 feet away. If the motor revs, you found a leak. Check around TBI unit, intake manifold etc...

Please be careful, let the previous spots dry before doing another, don't spray near alternator. It takes me less then two minutes to check an entire engine and I have never had one blow up... it'll just be a flame up real quick like when you seat a bead of a tire on a wheel...

 

[KeyBlazer]

Ok, will have a CO2 extinguisher handy!

 

[KeyBlazer]

Drove it to work today... ran about the same, bucking and surging at idle, but ran good and clean on the freeway.
Check engine code popped up, so I checked it at lunch.
32, and 33.
Decided to check the EGR vave by pushing it up under the diaphram.... it went up and stayed UP!
I unbolted it and it was stuck in the up position.
Then I spotted the problem!
The top of it was bent over slightly, so the pintle was not running straight up and down... A vice and a mallet soon had it free!
I think i bent it with the hoist when I put the motor back in!
Put it back on and we are running smooth!

Drove it home, and no check engine light!
Gonna try and get it smogged tomorrow now!

 

[KeyBlazer]

JUst got back from the Smog station...
IT PASSED!
So well in fact that the guy said wow!
Here are the numbers so you guys can see...

Test = HC(PPM)
Max allowed 172 @15mph and 107 @25mph
My Sub was 54ppm @15MPH and 27ppm @25MPH

Test CO%
Max allowed 1.93 @15mph 0.03% and 2.23 @25mph
My Sub was 0.03% @15MPH and 0.03% @25MPH


Test= NO(PPM)
Max allowed 2263 @15mph 102 and 2175 @25mph
My Sub was 102ppm @15MPH and 90ppm @25MPH


Not bad when you consider that I just rebuilt the motor at 165k but did not bore it, just rehoned the bores and new rings and bearings, a new RV cam and lifters and cleaned up the head...

The thing that gets it done is a Carsound HiFlow Cat and 3" mandril bent exhaust that I put on 6 years ago!

 

[Thunder]

Great! Glad you got it running good. Just wondering? What kind of RV cam did you put in?

 

[KeyBlazer]

It is a Melling MTC 6 camshaft.
I cut and paste the specs below

MTC-6 EXH. 40o BBC 12o BTC 208 86o BBC 32o ATC 298 .270 .459 116 1.7 HYD.​

INT. 6o ATC 30o ABC 204 36o BTC 72o ABC 288 .270 .459 108 HYD.

 

[Thunder]

I like Melling cams for TBI. Nice to see they work in BBC as well as SBC. They just seem to wake the engine up and work well without having to get a chip burned for them. Plus the price is right

 

[KeyBlazer]

Well, its running and passed smog, but running right it is not!

I noticed at constant throttle position on the freeway, its surging and not running smoothly. No codes showing.
I also got 6.6mpg on the last tank!
What should the ignition timing be?
I think it says 4btdc on the underhood plate...

 

[eagle mark]

Still think you should check fuel pressure and change the filter. We didn't find any vacuum leaks around the TBI unit correct? They are notorious for vacuum leaks around the base.

Hmmm. I'm not remembering if the 454 was different then the SBC were you disconnect a wire and set the timing to 0, then reconnect wire... maybe more coffee will help....

 

[dyeager535]

Sounds like EGR to me. Could be a few things, you can always unplug the EGR valve solenoid and see if it runs better during the exact same conditions.

 

[79BRUISER]

I just purchased a 454 tbi, so I'm subscribing