TBI 454 - A Few Ongoing Gremlins and Upgrade Questions

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Evil Crew Cab

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Steven
Truck Year
1987
Truck Model
V30 CC SRW Conversion
Engine Size
454 TBI/4L80E/NP205/D60/Gen 2 14BFF
Let me start off by listing the vehicle info and upgrades I've made to the truck/engine this far...

1987 V30 Crew Cab TBI 454 (60,000 original miles) with a 4L80E on a Compushift II Standalone Controller.

The truck pretty much sat for 16 years before I bought it. A lot of parts/wiring/sensors had issues when I brought the truck home so I went through a huge list of fixes!

- New MSD cap & rotor
- New MSD Blaster 2 coil
- New DUI DynaMod Ignition Module
- New MSD Super Conductor Wires
- New NGK 5 heat range plugs
- New upper and lower TBI gaskets
- New PCV Valve
- New NTK 1-wire o2 sensor
- New vacuum lines throughout engine bay
- New various wiring connectors as most were broken
- New Severe Duty Fan Clutch
- New OEM style 4-core radiator (only because I nicked the new one the previous owner installed while changing the fan clutch)
- 185* Robert Shaw Drilled T-Stat and all new hoses
- New A/C compressor and full 134A conversion with new pressure switch and all new o-rings
- Truck would not idle below 1,900rpm and I found the wiring to the front coolant temp sensor had been joined using 3M jelly bean crimp connectors and they failed. Solder and heat shrink fixed this.
- The EGR system started acting up a few weeks after starting to drive the truck, stumbling and bucking whenever I got into the throttle under load. After pulling the vacuum line off the EGR valve and finding this solved the problem, I replaced the EGR valve and solenoid with new AC Delco pieces. Problem still existed so I plugged the vacuum line internally and reconnected everything. Truck runs great but the EGR is simply for looks now.
- Both exhaust manifolds were cracked and check valves in the AIR tubes were bad, along with the AIR hard pipe that runs around the back of the engine to the driver side. I went ahead and found the last NOS hard pipe in the gm dealer network, got all new soft line and clamps, new AC Delco check valves, new Dorman manifolds and installed everything
- The passenger fuel tank never worked when I bought the truck and after diagnosing it as a faulty fuel pump we took the bed off and found the rubber hose between the pump and the pickup had rotted. So we flushed both of the tanks, replaced both pumps and soft lines with submersible hose, new Dorman buckets with new level sensors (level sensor in passenger side tank were bad as well) and new fuel filter.
- I also fully rebuilt the TBI unit with brand new Delphi injectors and new FPR.

There is a bunch of stuff I'm missing, but I basically replaced everything since the truck sat for so long!

As I've been restoring the truck I finished the 4L80E swap, lift/tires/wheels/suspension/steering, all the interior stuff and moved into working on the performance side of things and I have a few issues I need help with.

ISSUE #1 - Since I bought the truck, I have noticed that I always have an issue when I get off the freeway after cruising for a long distance (5+ miles) where the truck stumbles when I come to a stop at the freeway off ramp. I initially attributed this to "highway cooling" of the o2 sensor as I did replace it during my initial work but it was still a 1-wire unit. This issue will always clear itself up after 45 seconds or so and I get no SES lights/codes.

I just finished the entire exhaust system, Doug's Tri-Y's, Magnaflow 59956 spun Metallic core cats, Magnaflow 12226 mufflers and all 2.5" piping. When I did this work, I upgraded to an NTK 21003 3-wire o2 sensor thinking this would resolve the idle issue when getting off the freeway, it definitely made things better but it's still occurring.

ISSUE #2 - During the summer, the coolant temps have been fine whenever cruising on flat ground but during steep hills, whether going 25mph or on the freeway going 65mph, the truck with heat up past 220* even with the 185* Robert Shaw T-Stat, new radiator and new fan clutch. I've never had a truck do this so I'm wondering if this is common...

ISSUE #3 - Not really an issue, but wondering what route to take with tuning, where should I look for a solid performance chip? Should I also upgrade anything else in the ignition, like adding an MSD 6AL or Street Fire box? I am getting ready to swap the iron intake manifold for the Edelbrock 3764 TBI intake so any other thoughts on items to upgrade while I am doing the intake would be helpful!

Any help or insight on any of these topics is greatly appreciated! Thank you in advance!
 

Jims86

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Location
Patterson,Ca
First Name
Jim
Truck Year
1986
Truck Model
K10 Suburban Silverado
Engine Size
5.7 TBI
Let me start off by listing the vehicle info and upgrades I've made to the truck/engine this far...

1987 V30 Crew Cab TBI 454 (60,000 original miles) with a 4L80E on a Compushift II Standalone Controller.

The truck pretty much sat for 16 years before I bought it. A lot of parts/wiring/sensors had issues when I brought the truck home so I went through a huge list of fixes!

- New MSD cap & rotor
- New MSD Blaster 2 coil
- New DUI DynaMod Ignition Module
- New MSD Super Conductor Wires
- New NGK 5 heat range plugs
- New upper and lower TBI gaskets
- New PCV Valve
- New NTK 1-wire o2 sensor
- New vacuum lines throughout engine bay
- New various wiring connectors as most were broken
- New Severe Duty Fan Clutch
- New OEM style 4-core radiator (only because I nicked the new one the previous owner installed while changing the fan clutch)
- 185* Robert Shaw Drilled T-Stat and all new hoses
- New A/C compressor and full 134A conversion with new pressure switch and all new o-rings
- Truck would not idle below 1,900rpm and I found the wiring to the front coolant temp sensor had been joined using 3M jelly bean crimp connectors and they failed. Solder and heat shrink fixed this.
- The EGR system started acting up a few weeks after starting to drive the truck, stumbling and bucking whenever I got into the throttle under load. After pulling the vacuum line off the EGR valve and finding this solved the problem, I replaced the EGR valve and solenoid with new AC Delco pieces. Problem still existed so I plugged the vacuum line internally and reconnected everything. Truck runs great but the EGR is simply for looks now.
- Both exhaust manifolds were cracked and check valves in the AIR tubes were bad, along with the AIR hard pipe that runs around the back of the engine to the driver side. I went ahead and found the last NOS hard pipe in the gm dealer network, got all new soft line and clamps, new AC Delco check valves, new Dorman manifolds and installed everything
- The passenger fuel tank never worked when I bought the truck and after diagnosing it as a faulty fuel pump we took the bed off and found the rubber hose between the pump and the pickup had rotted. So we flushed both of the tanks, replaced both pumps and soft lines with submersible hose, new Dorman buckets with new level sensors (level sensor in passenger side tank were bad as well) and new fuel filter.
- I also fully rebuilt the TBI unit with brand new Delphi injectors and new FPR.

There is a bunch of stuff I'm missing, but I basically replaced everything since the truck sat for so long!

As I've been restoring the truck I finished the 4L80E swap, lift/tires/wheels/suspension/steering, all the interior stuff and moved into working on the performance side of things and I have a few issues I need help with.

ISSUE #1 - Since I bought the truck, I have noticed that I always have an issue when I get off the freeway after cruising for a long distance (5+ miles) where the truck stumbles when I come to a stop at the freeway off ramp. I initially attributed this to "highway cooling" of the o2 sensor as I did replace it during my initial work but it was still a 1-wire unit. This issue will always clear itself up after 45 seconds or so and I get no SES lights/codes.

I just finished the entire exhaust system, Doug's Tri-Y's, Magnaflow 59956 spun Metallic core cats, Magnaflow 12226 mufflers and all 2.5" piping. When I did this work, I upgraded to an NTK 21003 3-wire o2 sensor thinking this would resolve the idle issue when getting off the freeway, it definitely made things better but it's still occurring.

ISSUE #2 - During the summer, the coolant temps have been fine whenever cruising on flat ground but during steep hills, whether going 25mph or on the freeway going 65mph, the truck with heat up past 220* even with the 185* Robert Shaw T-Stat, new radiator and new fan clutch. I've never had a truck do this so I'm wondering if this is common...

ISSUE #3 - Not really an issue, but wondering what route to take with tuning, where should I look for a solid performance chip? Should I also upgrade anything else in the ignition, like adding an MSD 6AL or Street Fire box? I am getting ready to swap the iron intake manifold for the Edelbrock 3764 TBI intake so any other thoughts on items to upgrade while I am doing the intake would be helpful!

Any help or insight on any of these topics is greatly appreciated! Thank you in advance!

Where is your o2 sensore located? Had a guy with tri Y's, and the sensor was mounted in one of the primary y pipes, and was only reading from 2 cylinders.
 

Evil Crew Cab

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V30 CC SRW Conversion
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454 TBI/4L80E/NP205/D60/Gen 2 14BFF
Hey Jim, thank you for replying! :) I put the o2 bung down in the collector (hence the 3-wire upgrade).
 
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Jims86

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Hey Jim, thank you for replying! :) I put the o2 bung down in the collector (hence the 3-wire upgrade).

Ok, good. Any trouble codes? a bad VSS would cause the offramp issues.
Also, if you replaced the IAC wiring, the 2 blue wries are swapped on the 454 IAC plug, from what they are on the sbc tbi harness.
You may alsomwant to check the pickup coil in the distributor, they have been known to come loose, or even crack, throwing the timing off.
 
Last edited:

Evil Crew Cab

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Location
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Steven
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1987
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V30 CC SRW Conversion
Engine Size
454 TBI/4L80E/NP205/D60/Gen 2 14BFF
I randomly throw a 32 code on the highway now that I have the vacuum line from the solenoid to the valve plugged. Before that, nothing.

As for anything else, no codes! The truck runs great otherwise.
 

Evil Crew Cab

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V30 CC SRW Conversion
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454 TBI/4L80E/NP205/D60/Gen 2 14BFF
Ok, good. Any trouble codes? a bad VSS would cause the offramp issues.
Also, if you replaced the IAC wiring, the 2 blue wries are swapped on the 454 IAC plug, from what they are on the sbc tbi harness.
You may alsomwant to check the pickup coil in the distributor, they have been known to come loose, or even crack, throwing the timing off.

As for VSS, the signal from the speedo works perfect for the cruise control so I don't see how this would affect the fueling after a decel off the freeway. Remember, my truck is originally a 454/400/205 truck with a manual speedo cable from the t-case. The 4L80E is on a standalone with the ISS and OSS in The Trans controlling the shifting through the Compushift II TCM.

The IAC is actually the only plug I didn't have to re-wire and the IAC is working perfectly, I have three complete assembled 454 TBI units and all three IAC's tested fine, so that isn't the issue.

With the pickup coil, you really think this would cause the stumbling issue? The truck runs great everywhere else and timing doesn't seem to be an issue.
 
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Jims86

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As for VSS, the signal from the speedo works perfect for the cruise control so I don't see how this would affect the fueling after a decel off the freeway. Remember, my truck is originally a 454/400/205 truck with a manual speedo cable from the t-case. The 4L80E is on a standalone with the ISS and OSS in The Trans controlling the shifting through the Compushift II TCM.

Its kinda like the old vacuum kicker solenoid on a carbureted car, it would hold the throttle open a little when coming to a stop. the VSS tells the ecm you are still at speed, and feathers the IAC so the engine does not stall out. your VSS is mounted behind your speedometer.
I would also recommend going back to a 195* thermostat, as long as your gauge does not go into the red, dont worry about it...the ECM needs to see the proper temps for the fuel and spark tables.
Also, look up "the big 3" thread here...wouldnt hurt to bolster up the electrical system too.
 
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Evil Crew Cab

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V30 CC SRW Conversion
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454 TBI/4L80E/NP205/D60/Gen 2 14BFF
I totally spaced on that, I upgraded to the factory aux battery tray on the driver side and isolated it with a 200 amp solid state isolator, full 4 gauge welding cable for ALL wires.

All grounds to both batteries were done as follows:

- both batteries to frame rail
- both batteries to body (sheetmetal)
- both batteries to engine block
- engine block to both frame rails
- body to frame rails (4 points - 2 up front in the engine bay and 2 using the rear seat belt bolts through the body)

All interconnects were done with soldered connection in copper ring terminals

I will look into the VSS area, I may have an NOS VSS module/box laying around to test, but worse case do you think the speedo may have an issue with the optical output?
 

Evil Crew Cab

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Damn double posts! :D
 

Evil Crew Cab

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V30 CC SRW Conversion
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454 TBI/4L80E/NP205/D60/Gen 2 14BFF
Well, the stumble on highway off ramps seems to have all but disappeared! It hasn't done it since I first drove it with the headers and exhaust done!

The truck also passed the sniffer with flying colors for smog so things must be working!

I guess my last questions to be answered are the coolant temps during hotter weather and the ignition system...any insight because I see totally mixed reviews on adding an MSD box to the TBI system! Some people swear by them and other say they are more trouble than anything else!

What should I do with my air intake? Some people say just ditch all the tubing and run the K&N filter in the stock housing with the inlet tube open.

Also, anyone running the Edelbrock TBI specific manifold (3764)? Will it help in the power department?
 

Jims86

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K10 Suburban Silverado
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5.7 TBI
Well, the stumble on highway off ramps seems to have all but disappeared! It hasn't done it since I first drove it with the headers and exhaust done!

The truck also passed the sniffer with flying colors for smog so things must be working!

I guess my last questions to be answered are the coolant temps during hotter weather and the ignition system...any insight because I see totally mixed reviews on adding an MSD box to the TBI system! Some people swear by them and other say they are more trouble than anything else!

What should I do with my air intake? Some people say just ditch all the tubing and run the K&N filter in the stock housing with the inlet tube open.

Also, anyone running the Edelbrock TBI specific manifold (3764)? Will it help in the power department?
*The only cooling system changes I recommend is adding a trans cooler, and an oil cooler if you dont already have one. A bigger/thicker radiator would be better than a cooler thermostat, since TBI is really sensitive, and reliant upon coollant temp.
*Stock ACDelco should be sufficient as far as ignition...any more is a waste of money, and not as reliable.
*stock air intake is very efficient, and is only improved by making sure the hose can draw from an outside source...like in front of the radiator support, through one of the knockouts. Wix or NAPA gold stock air filter is sufficient, especially if you have the extra tall aircleaner lid.
*The edelbrock TBI intake is a better flowing design, and will compliment your exhaust modifications ver nicely.
 

Evil Crew Cab

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V30 CC SRW Conversion
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454 TBI/4L80E/NP205/D60/Gen 2 14BFF
Okay, sweet! When I did the 4L80E swap, I upgraded to all new 3/8" trans cooler lines and a big cooler up front behind the electric fan and I will be adding an full engine oil cooler as well. I already have the 4-core radiator so I don't know what I can upgrade to fr here. I already have the severe duty fan clutch as well.

As for the intake, I have a K&N filter with the full stock intake tubing to the knockout in tact so I am going to work on a dual snorkel intake and I am going to redesign the plastic insert in the knockout to increase direct airflow to create a ram air effect...I'll update with photos as I go.

And I just picked up the intake manifold and throttle cable bracket and all associated parts so once I get my new (used) cast Gen V valve covers cleaned up and ready to go, I'll get the intake installed! :)

Thanks for all your help so far! Any other advice for my truck/engine? With 60,000 miles on the engine, I really don't want to break into the long block just yet! ;)
 

Jims86

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Okay, sweet! When I did the 4L80E swap, I upgraded to all new 3/8" trans cooler lines and a big cooler up front behind the electric fan and I will be adding an full engine oil cooler as well. I already have the 4-core radiator so I don't know what I can upgrade to fr here. I already have the severe duty fan clutch as well.

As for the intake, I have a K&N filter with the full stock intake tubing to the knockout in tact so I am going to work on a dual snorkel intake and I am going to redesign the plastic insert in the knockout to increase direct airflow to create a ram air effect...I'll update with photos as I go.

And I just picked up the intake manifold and throttle cable bracket and all associated parts so once I get my new (used) cast Gen V valve covers cleaned up and ready to go, I'll get the intake installed! :)

Thanks for all your help so far! Any other advice for my truck/engine? With 60,000 miles on the engine, I really don't want to break into the long block just yet! ;)
I personally would ditch that K&N, for a large NAPA gold or Wix filter.
Do you have the round insert in the radiator support, or is it the long virtical plastic box?
There really wiil be no useful ram effect, but air temp is the big factor.
 

Evil Crew Cab

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V30 CC SRW Conversion
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454 TBI/4L80E/NP205/D60/Gen 2 14BFF
I have the short air filter, not the tall one. I have the insert that mounts into the knockout in the core support with the barrel type box mounted to it, then the scrunchy plastic tube that mounts to the metal filter housing. I did remove the constricting Venturi insert inside the barrel.
 

Jims86

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5.7 TBI
I have the short air filter, not the tall one. I have the insert that mounts into the knockout in the core support with the barrel type box mounted to it, then the scrunchy plastic tube that mounts to the metal filter housing. I did remove the constricting Venturi insert inside the barrel.

Got pics of this venturi doohickie?
 

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