Who's Online
0 registered (), 2 Guests and 0 Spiders online.
Key: Admin, Global Mod, Mod
Newest Members
FesterB, Dexter, 19MC70, chevyz1, SirJ
136 Registered Users
Top Posters
Allan 1966
Greg 1911
kc8oye 1433
Phil 793
Sam/bones 659
Davey 494
MC87SS 383
MONTE7071 312
Rob 210
Joe 179
Forum Stats
136 Members
23 Forums
907 Topics
9194 Posts

Max Online: 63 @ 02/04/13 03:15 AM
Topic Options
#9296 - 03/15/17 03:18 AM 1994 Silverado 5.7 L / TBI Issues.
Greg Offline

Founder
SBC Mouse V8
*****

Registered: 02/01/11
Posts: 1911
Loc: Middle East
I'm scratching my head here fellas... I Just dropped a rebuilt stock 5.7 into a 94 Silverado with 5.7 L TBI

The only difference in the old engine we pulled and this one is the TBI, I opted to go with a Holley TBI - Part Number 502-9 which is said by Holley to be a direct replacement for the stock TBI, with a larger bore to flow more air CFM 670 - vs I think 600 from the stock. If I read things correctly it doesn't even have larger injectors in it, just a bore and some smoothing on the barrels.

I cannot get this thing dialed in...it's driving me nuts.

Every sensor on the engine has been replaced :
MAP - New
TPS - New (With the Holley)
Engine Coolant Sensor - New
Knock Sensor - New
IAC - New

No Engine codes - it was throwing a Knock Sensor code - but that is fixed now.

So here's what happens:

It starts fine - fires right up - Timing is set to 0 degrees TDC as specified in the manual.
It revs fine sitting in park
It will sort of stumble a bit at times but you can hear the PCM adjusting it back and it will smooth out.

Put it in drive and go down the road, no power, and it stumbles and stalls constantly.

Vacuum was tested it's 19 - 20 @ idle

I'm seeing black smoke at start up and when you rev it - so it's running way too rich it seems. It does not indicate to me an issue with not enough fuel, if anything it's getting too much...

Just wanting to know if any one out there has done one of these mid 90's TBI Engines and what sort of issues you might have run into, because quite frankly - I'm at wits end here. I'm about to rip the Holley off and go back to a stock TBI and see if that does anything - because the one wild card here is this Holley TBI and it's most certainly at this point a fuel issue as I've ruled out everything else... or did I ?
_________________________
Takin' the road less traveled....as always.

https://volunteerpowderservice.com/

Top
#9297 - 03/17/17 12:38 AM Re: 1994 Silverado 5.7 L / TBI Issues. [Re: Greg]
Allan Online   content
Resident Ogre
SBC Mouse V8
*****

Registered: 01/27/11
Posts: 1966
Loc: Wherever I am
Sounds like an IAC motor issue or IAC not adjusted properly.
_________________________


Top
#9298 - 03/17/17 05:35 AM Re: 1994 Silverado 5.7 L / TBI Issues. [Re: Greg]
Allan Online   content
Resident Ogre
SBC Mouse V8
*****

Registered: 01/27/11
Posts: 1966
Loc: Wherever I am
I did a little more reading on that TBI. I actually have a friend with one on her Firebird and she mentioned that she had issues like that. It turned out to be a bad fuel filter for her. She mentioned that although it is not a high pressure system, it does need to maintain 11-12psi to function correctly.
_________________________


Top
#9299 - 03/17/17 02:11 PM Re: 1994 Silverado 5.7 L / TBI Issues. [Re: Greg]
Greg Offline

Founder
SBC Mouse V8
*****

Registered: 02/01/11
Posts: 1911
Loc: Middle East
Well whatever it is - this POS is going back to Summit post haste...

We rebuilt the stock TBI finally, slapped it in .. and Viola'!
No Black smoke, no surging idle, no missing, purrs like a kitten and has plenty of power - well as much power as could be had in a stock 1994 5.7 - A whole whopping 190 HP...LOL

On a related note....being a good Samaritan - I figured I'd write a review for Summit, so other buyers could be informed of some of the pitfalls associated with this particular unit.. and the rare times I do review a product, I am detailed about it, so people know exactly what I am saying. I hate mouth breathing morons - dare I say "RETARDS" that post useless information in reviews... it's a pet peeve of mine.

Any how after careful thought and writing I Hit submit - BZZZZZT! "Your post contains offensive language - please remove and re-submit".

WHA-Huh? Now I know I was a little tweaked after 4 days of trying to get this thing to settle out and work, but I didn't put anything bad in the post .....

Let me think ... think... think... Oh wait I used the word 'retard' to describe the troubleshooting we did with timing.... REALLY?
So I removed it and post went right through. SMFH

And .... there it is folks the PC Pu$$y crowd has reached it's dirty di*k skinners into the last bastion of freedom... the gear head world.... you cannot use the word "retard" on Summits website.

Well you know what - that's just f'n RETARDED Summit... RETARDED I SAY !!

175 Years of automotive language IRT to ignition timing and some f'n snow flake in the bowels of the internet is screaming at car guys "you can't say that ... it's offfffensive"

Well here's what I say to that ....

Shut yer pie hole you f'n retard!! banghead

I honestly think I am more PO'd about the PC Police F'n with my 1st Amendment rights on a web site than I am after wasting 4 days pissing away time with Holley's POS TBI system..... horse
_________________________
Takin' the road less traveled....as always.

https://volunteerpowderservice.com/

Top
#9300 - 03/18/17 02:35 AM Re: 1994 Silverado 5.7 L / TBI Issues. [Re: Greg]
Allan Online   content
Resident Ogre
SBC Mouse V8
*****

Registered: 01/27/11
Posts: 1966
Loc: Wherever I am
So what do they want you to say, Anti-Advanced?

That is just RETARDED! laugh
_________________________


Top
#9301 - 03/26/17 02:50 PM Re: 1994 Silverado 5.7 L / TBI Issues. [Re: Greg]
Greg Offline

Founder
SBC Mouse V8
*****

Registered: 02/01/11
Posts: 1911
Loc: Middle East
Haven't had a whole lot of time to post - but what a nightmare this has turned into...

We switched out the TBI - It ran fine right up until about - oh 30 miles or so and suddenly the Engine is loosing oil pressure at idle after it warms up. 60-70 PSI at start up, but as soon as it gets warm, no oil pressure and the check gauges light comes on.

As far as I can tell it's probably bad clearance on the main bearings.... sigh.
_________________________
Takin' the road less traveled....as always.

https://volunteerpowderservice.com/

Top
#9302 - 03/30/17 01:35 AM Re: 1994 Silverado 5.7 L / TBI Issues. [Re: Greg]
Allan Online   content
Resident Ogre
SBC Mouse V8
*****

Registered: 01/27/11
Posts: 1966
Loc: Wherever I am
That's a bummer. It's always somethin, just when you think you're winning the race..........
_________________________


Top
#9306 - 05/25/17 04:39 PM Re: 1994 Silverado 5.7 L / TBI Issues. [Re: Greg]
kc8oye Offline
Sofa King
SBC Mouse V8
*****

Registered: 01/27/11
Posts: 1433
Loc: Grand Blanc, MI
did you update the 'tune'? TBI engines are speed-density.. and are CRAZY sensitive to *any* changes in air flow.

my dad and I ported the heads on my 4.3L v6 (tbi) and ended up building a whole new tune for it.. (he was a GM powertrain engineer)
_________________________
13.970 @ 98.37mph that NOS bottle in my closet says I see 12's this summer.

Top



Moderator:  Davey 
July
Su M Tu W Th F Sa
1
2 3 4 5 6 7 8
9 10 11 12 13 14 15
16 17 18 19 20 21 22
23 24 25 26 27 28 29
30 31
User_Photos
529/thumbs/bathroom_002.jpg
by Greg
507/thumbs/Paint_prep_and_wireing_002.jpg
by Greg
507/thumbs/Paint_prep_and_wireing_008.jpg
by Greg
510/thumbs/intake_005.JPG
by Sam/bones
505/thumbs/DSCF0007.JPG
by Allan