I have a '94 F350 4X4 with a 351W. I am thinkingabout removing all the EGR, and air pump stuff to increase performance. Do I need to reprogram the computer? I will need a different belt, any idea where to look? Will removing this stuff help out like I'm hoping???

 

Removing/blocking the EGR will give you zero HP. The EGR isn't active at open loop WOT; it only costs power (and not very much) when you're in part-throttle closed loop.

The air pump probably costs you something on the order of 2 HP, hardly worth the effort of removing. The air pump is necessary for proper functioning of the catalytic converter. If you have to pass smog inspection, you need to keep it

 

Don't mess with it. Maintain all the emissions systems, as well as the rest of the truck.

 

The cat has already been removed. There are no smog inspections here. I need to rebuild the motor, and I would like to eliminate any unnecessary stuff. I also want to add headers and don't know how many I'll find with allthe right ports. The main concern is if I remove the air pump will it effect the computer?

 

i took all that crap off my truck too but if you are going to do headers etc you need to look into doing a mass air swap

 

T

I'll tell you what I did. I have a '95 F-150 4X4 with a 351w with PS & AC.

I had 2 smog (A.I.R.) pump failures in 18 months. When the third pump started making a racket indicating impending failure, I decided to simply cut it out of the loop with a shorter serpentine belt.

I had to do some measurement with a steel tape, and then some experimentation with a number of belts. I found that a 94.5", 6-rib belt was an adequate replacement for the original 102" belt. The 94.5" belt was just a "hair" too long because my belt tensioner was original & weak. But the 94.0" was way too short & the 95.0" was way too long (Gates makes a 94.2" which I have not tried). But the 94.5", while just a bit looser than the original, seems to work fine & has not slipped off yet after a few months. And the smog pump is out of the circuit and no longer makes that horrible racket. By the way, the belt was a 945K6 Goodyear belt from Advance Auto ($15). Cheap belt, but I just wanted to see if it would work at all.

Also, since the smog pump is operated in the circuit by the computer primarily during warm-up and during ECM diagnostic routine, it's absence does not affect normal running. I have no codes set.

Don't know much about the Big Boys (F350's) but hope this will help.

 

The secondary air pump isn't used during any cold-engine operation. Nor is it used for any EEC diagnostic. It's only used after the engine & cats warm up.

 

One exception to that, occurs only on vehicles which have secondary air injection nozzles in the exhaust ports.

During cold driveaway, the secondary air pump sends air to the air injection nozzles. This is because the intentionally over-rich settings for cold driveaway can leave unburned HC in the exhaust. By adding air at the exhaust port, the unburned HC is burned there rather than in the cat. This prolongs cat life. Once the engine warms up all the secondary air is sent to the 3 way cat.

 

I've never read documentation supporting that, but #1 in this caption suggests that that's not possible since "cold" (below 60°F) driveaway is below the operating limits of the ECT & IAT.

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AFAIK, the only pre-'96 truck engines with air nozzles in the exhaust are the 4.9Ls, but V8s still have upstream air. It goes in at the back of the heads & flows thru a journal to each exhaust port.

 

On pre-computer trucks the secondary air pump is used during cold starts and certain other conditions. On processor controlled trucks I would think it would be the same, but the computer controls it.

Based on JLF's post the EEC might not actually monitor the pump, but the EEC can store trouble codes for improper bypass and/or divertor valve operation. If it only checks the solenoids and not the actual air flow, removing the pump alone might not throw a code or CEL.


The actual pump seems to spin fairly easily, so I can't see any gains worth removing it for personally.

 

On vacuum-controlled engines, the TVVs prevent any pump air from entering the exhaust before the engine is warm, so I think you're wrong about that, too. Ford has never monitored the actual air flow from the pump in any way. And the TAB/TAD codes aren't set for improper operation: only for circuit faults.

 

Haynes and a number of code scanners reference codes that indicate flow problems, not just circuits. These cover inoperative system, lack of bypass, improper diverter, and inadequate flow.

Obviously if the ciruit that controls a function fails, the function fails. It still narrows down what to check for.

 

The code definitions are worded as though they describe a flow problem, but the trucks have no sensors for the flow, so those codes actually only set for circuit faults. There are no feedback circuits to detect function, either, other than the EVP. But it doesn't actually check the VALVE position; it checks the DIAPHRAGM position, and the valves are known to break away from the diaphragm pushrods, so it's not a true feedback.

 

Removing the EGR will not improve performance and in fact could cause the engine to ping at WOT, removing the air pump will not set any codes but you may need to install an idler pully in place of where the air pump was to maintain the proper routing of the belt. That is unless it use a seperate belt for the air pump. You also can leave the airpump itslef in place and just do away with the diverter valve and all of the associated vac. hose and air supply hose to the exhaust and engine. The airpump does not cause much parasitic horsepower lose, the only problem you could face would be a bearing failure in the pump itself and believe it or not the use the same bearing as most idler pulleys use too.

 

The EEC systems use both the ECT and the O2 sensor (once in closed loop) for feedback. If there was no feedback, it wouldn't produce the different codes, even if the code could isolate the circuit.

The upstream air at startups is due to the fact that the cats don't work for crap until warm, and can be damaged by a rich mixture. That's one of the primary reasons the circuit exists in the injected trucks. Once up to temp the system doesn't dump air unless required as indicated by the ECT sensor.

StrangeRangers statement was correct by all sources I have ever seen. If you have something to the contrary cite the source rather than claim to know what Haynes, Ford, and the code reader companies don't.