Got a puzzler

[ndahmenjr]

I got some issue going on with my Bronco, 1990; full size; 351; 5.8L; auto; cold air int, and I am not sure how to solve it. So I will go through the problem and see if anyone else has an idea.

If I start the engine then open and shut the driver door the engine stutters and 80% of the time it dies. If I turn the wheel at a medium pace while idling it will stutter and sometimes die. If I put it in reverse it will die most the time. Start it up put it in forward and if I don't put gas to it it will die. If I am driving slow, <20, and do not put gas to it it will die. Every time it dies it will start right back up again. If I put gas to it it will rev fine up to 30 and then drop into low RPM like it skipped third. I then pump the peddle and it kicks into high RPM for about 5 seconds. If I am driving 30-40 and holding the gas at a cruise the RPM will rise and fall constantly.

I checked that vacuum last weekend and found the TAB (pink line and now tan) was not connected to anything. I do not have an AIR BPV, I can take pics if you want, I search and searched for it and finally capped it. Also the yellow line is capped. Anyhow any tips would be great.

Nick

 

[Seabronc]

I might suggest that you have more than one problem. The door thing suggests a short or bad connection. Check the wires along the frame on the left and side in the engine compartment and under the dash, Look for a wire near a metal edge that may be worn through. Also, remove the connector where the wire pass through the fire wall. It may have corroded contacts. Remove it, clean the contacts and re-hook it up. Also check the codes from your computer. Look in the how to forum for the procedure for checking codes.

Good luck,

 

[Ty V.]

It may be worth checking your idle air control valve, because my Bronco had some similar problems and putting in a new valve fixed it right up.

-Ty

 

[miesk5]

yo ndahmenjr,

WELCOME!

Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19 @ http://broncozone.com/topic/14269-code-reader/page__pid__74587__mode__threaded

Look Codes up in my broncolinks.com site using the new Search function.

And Post em here according to

KOEO

&

KOER

---------



Secondary Air Injection System Overview & Diagram; "...Secondary Air Injection system consists of a belt-driven Air Pump, single or dual AIR Diverter (AIRD) valve(s), an AIR Bypass (AIRB) valve, and AIR Bypass solenoids, air silencer/filter, Powertrain Control Module and connecting wires and vacuum hoses. The Belt-Driven Secondary Air Injection system provides either upstream/bypass air or upstream/downstream/bypass air. The number of these system configurations vary significantly with AIR Bypass (AIRB) and AIR Diverter (AIRD) valve combinations (Figure 179). 2. The PCM provides one or more signals that enable one or more AIR Bypass solenoids. 3. The AIR Bypass solenoids control one or more AIR Bypass valves and/or AIR Bypass Diverter Valves in order to route secondary air depending upon the specific configuration. 4. The belt-driven Air Pump is operational any time the engine is running..." read more

Source: by Steve83 (Steve, That dirty old truck) at http://www.supermotors.net/registry/media/589993

in a 90 5.8; "...

"...Be advised that the ACV (Air Control Valve) is the TAD (Thermactor Air Diverter) Valve and the AIR BPV is the TAB (Thermactor Air Bypass) Valve.

The VRESER is the Vacuum Reservoir Can where the red & black vacuum lines plug into;

On my 1990 ex-5.8L, the Yellow Vacuum Line goes from the TAD Solenoid (driver's side forward solenoid) to the TAD (Diverter) Valve located at the rear of the Intake Manifold.

The Pink Vacuum Line goes from the TAB Solenoid (driver's side rear solenoid) to the passenger side (adjacent to the Vacuum Reservoir Can) and down to the bottom of the TAB (Bypass) Valve. Note that my Pink Vacuum line appears Yellowish in this pic and is not yet connected to the base of the TAB Valve as I was working up a solution at the time.

You have to climb up onto the engine to feel the Diverter Valve or remove the Intake Manifold. I'd rather climb up using plans, ala a scaffolding type set-up; maybe remove hood depending on circumstances such as me now, w/ backache..."

First check that the two vacuum lines are connected to the Vacuum Reservoir (coffee can) and the resevoir is in good repair with no leaks on the bottom. Frequently the can leaks or the vacuum lines are accidentally knocked off. Check the vacuum hose to the bottom of the Bypass Valve. Check the vacuum hose to the Diverter Valve. Check the vacuum hoses to the TAB/TAD Solenoids. Then check your TAB/TAD Solenoids. These are common easy to miss problems. Once these are ruled out all that is left is: Thermactor Air Supply Hoses. One-way Check Valves. Main TAB/TAD Valves..."



Source: by Seattle FSB (SeattleFSB) at http://www.supermotors.net/registry/media/783571

See all his pic there, click Next

Vacuum Line (Hose) Sourcing; "...Get the Silicone Boost/Vacuum Hose Engine Dress Up Kit and then an additional 10' of 4mm vacuum hose in the color of your choice. I used wire loom to protect the hose through the Intake Manifold, to the Diverter Valve and where it rubs on the Intake to the EVP: Silicone Intake Systems..."

Source: by Seattle FSB

Vacuum Leak Test; On an idling engine check for vacuum leaks using a mechanic's stethoscope with the probe removed, or a ~3' garden hose section. On COLD ENGINE only, use propane torch w/rubber hose attached, UNLIT or spray carb cleaner, when it gets to the the leak the RPMs will rise. Also check: vacuum hoses; intake manifold gasket & throttle body; PCV line; vacuum reservoirs: EGR Sys Vacuum Tank & 2ndry air (coffee can); AC, heater, defroster, vent control ckt & vacuum tank (plastic ball type), under dash & lines to heat/blend/etc. doors; power brake booster; cruise control ckt, etc. Where applicable; BEWARE OF BELTS/PULLEYS, FAN AND HOT ENGINE Source: by miesk5 at Ford Bronco Zone Forums

Vehicle Emission Control Information (VECI) Decal; Contains Vacuum Diagram & Calibration Parts List for 88 & UP. On-Line for Free at Ford. Click "Quick Guides" in left panel;

Scroll to & CLICK VECI Labels "Provides Vehicle Emission Control Information (VECI) and a related calibration parts list." Enter applicable info (need to know your Calibration number from your B-pillar sticker). Vacuum Diagram is the same as the one on the core support or hood or air filter cover. Suggest Right Clicking this Hot Link & Open in New Window

Source: by Ford @ http://www.motorcraftservice.com

Vacuum Line Acronyms & Color Codes;

EMISSION:

Red = Main vacuum;

Green = EGR function;

Yellow = from the TAD Solenoid (driver's side Forward Solenoid) to the TAD (Diverter) Valve located at the rear of the Intake Manifold (Distributor Advance in Carbureted Engines);

White = EGR vacuum (source);

Black = Mainly used for the Evaporative emissions control;

Black = Thermactor ACV or Diverter valve;

Pink = from the TAB Solenoid (driver's side rear solenoid) to the bottom of the Thermactor Air Bypass Valve (TAB or BPV/AIR Bypass (AIRB) valve); ACV (Air Control Valve) is the TAD (Thermactor Air Diverter) Valve (AIR Bypass (AIRB) and AIR Diverter (AIRD) valve combinations);

MAN VAC is Manifold Vacuum;

FPR is Fuel Pressure Regulator;

EGR is Exhaust Gas Re-circulation Valve

SOL V: Thermactor Air Diverter (TAD) Solenoid (SOL V) (AIRD) & Thermactor Air Bypass (TAB) Solenoid;

EVR is EGR Vacuum Regulator;

VRESER is the Vacuum Reservoir Can (Tank);

V REST on later years is Vapor Valve (Roll-Over @ Gas tank); V REST on earlier years such as 78/79 & SEABRONC's 83 is a Vacuum Restictor/Delay Valve, it restricts vacuum for a certain amount of time, on most engines a vacuum line from the carburetor base runs to a T & then to V REST to the distributor;

Carbon Can is Carbon Canister (Charcoal Canister, Vapor Canister, Evaporative Emission (EVAP) Canister);

MAP is Manifold Absolute Pressure Sensor;

AIR BPV is the AIR Bypass (AIRB) Valve, also called the TAB (Thermactor Air Bypass) Valve;

CPRV is Canister Purge Solenoid Valve/ Canister Purge Solenoid (CANP);

VCKV is Vacuum Check Valve;

CAT is catalytic converter;

ENG is engine;

PCV is Positive Crankcase Ventilation Valve.

Source: by Seabronc (Rosie, Fred W), Seattle FSB & miesk5