EGR Delete - Stalling issues
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Mountain Pass
Joined: Oct 2020
Posts: 112
Likes: 6
EGR Delete - Stalling issues
Background: I bought a 1994 Ford F150 5.8L V8 351W that has ~190K miles. The previous owner made some upgrades including BBK throttle body and BBK shorty headers and dual exhaust and deleted the EGR valve. Long story short, the truck stalls when coming to a stop when the engine gets to operating temp. There seems to be some sort of hiccup in the engine even when the car is in neutral if the throttle is engaged to low RPMs.
The truck has been in the shop for a while but nothing has been diagnosed. They have gone through a variety of sensor testing that have all come back in spec. My question is - is it possible that the computer is still expecting a reading from the emissions system even though it has been removed? Would that cause the symptoms I am experiencing? I have very little experience with troubleshooting this sort of thing but I'm trying to learn as much as I can and have done quite a bit of research on the issue. I appreciate any and all input!
The truck has been in the shop for a while but nothing has been diagnosed. They have gone through a variety of sensor testing that have all come back in spec. My question is - is it possible that the computer is still expecting a reading from the emissions system even though it has been removed? Would that cause the symptoms I am experiencing? I have very little experience with troubleshooting this sort of thing but I'm trying to learn as much as I can and have done quite a bit of research on the issue. I appreciate any and all input!
Thread Starter
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Mountain Pass
Joined: Oct 2020
Posts: 112
Likes: 6
ECU does not have after market chip plugged in. I bought a Quarterhorse with the hopes of being able to datalog the stock configuration to pinpoint the issue but I'm still learning how to best go about that. I believe the throttle body is bigger than the stock unit - but again I am still trying to learn all of this. I don't come from an auto or mechanical background at all so doing my best to learn as I go.
Other updates include lift kit, O/D transmission full rebuild, AC pump, new alternator, distributor cap, rotor, plugs and wires.
I will also note that the truck starts right back up immediately after stalling.
Other updates include lift kit, O/D transmission full rebuild, AC pump, new alternator, distributor cap, rotor, plugs and wires.
I will also note that the truck starts right back up immediately after stalling.
Last edited by bdwiggin; Jul 26, 2022 at 08:13 PM.
Hotshot
Joined: Jun 2015
Posts: 12,872
Likes: 2,445
Yes. Even the smaller twin 56mm BBK throttle body is bigger than stock.
Did the shop check for fault codes or are randomly testing sensors? The computer controls idle speed through the IAC motor. Have they don’t anything to see if the IAC is working? Is the torque converter not unlocking when coming to a stop.
Did the shop check for fault codes or are randomly testing sensors? The computer controls idle speed through the IAC motor. Have they don’t anything to see if the IAC is working? Is the torque converter not unlocking when coming to a stop.
Thread Starter
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Mountain Pass
Joined: Oct 2020
Posts: 112
Likes: 6
I checked for codes myself prior to sending to the shop and got the following:
Self test Codes:
121 - Closed throttle voltage higher/lower than expected. (Shop has since checked voltage and it is within acceptable range)
334 - EGR closed valve voltage high. (EGR has been deleted)
Continuous memory codes:
113 - Intake air charge temperature sensor above max voltage
118 - Engine coolant temp sensor above max voltage
128 - Manifold absolute pressure sensor failure / vacuum hose disconnected or damaged. (vacuum has since been tested and passed)
542 - Fuel pump secondary circuit fault
For the continuous memory codes - I did not reset the ECU prior to running my tests so I'm not sure how old those codes might be.
IAC has supposedly been checked. I'm not sure about the torque converter unlocking but given my research, that is on my list of potential issues. How would I go about testing for that?
Self test Codes:
121 - Closed throttle voltage higher/lower than expected. (Shop has since checked voltage and it is within acceptable range)
334 - EGR closed valve voltage high. (EGR has been deleted)
Continuous memory codes:
113 - Intake air charge temperature sensor above max voltage
118 - Engine coolant temp sensor above max voltage
128 - Manifold absolute pressure sensor failure / vacuum hose disconnected or damaged. (vacuum has since been tested and passed)
542 - Fuel pump secondary circuit fault
For the continuous memory codes - I did not reset the ECU prior to running my tests so I'm not sure how old those codes might be.
IAC has supposedly been checked. I'm not sure about the torque converter unlocking but given my research, that is on my list of potential issues. How would I go about testing for that?
Last edited by bdwiggin; Jul 26, 2022 at 08:37 PM.
Moderator
Joined: Jun 2003
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From: Calhoun GA
If you can monitor real time A/F ratios, from a separate A/F ratio monitor that utilizes a separate wideband O2 sensor, then that would be a good start. A larger throttle body can cause a noticeable tip-in-lean condition, and it can also cause the motor to cough/stall if the ECU is not tuned for it. Something else to check is vacuum pressure and MAF, and fuel pressure at idle, with the vacuum hose removed from the FPR.
Moderator
Joined: Jun 2003
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From: Calhoun GA
You may be looking at an ECU issue with all of those codes. Clear them and see if any of them come back, then troubleshoot.
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Mountain Pass
Joined: Oct 2020
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What is the recommended method to clear codes? I've read different things but disconnecting the negative to the battery has been the most recommended.. but I have no idea what I'm doing so some confirmation would be appreciated
Apologies in advance for any basic/stupid questions
Apologies in advance for any basic/stupid questions
Last edited by bdwiggin; Jul 26, 2022 at 08:46 PM.
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Moderator
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From: Calhoun GA
You can disconnect the negative battery cable, turn on the headlights to help make sure the 12v circuit is discharged and leave it disconnected for roughly 10 minutes. Or you can buy a cheap OBD-1 code scanner (ebay has some) that has the ability to read and clear codes. Connect the battery back, start it up/drive it and see if any of them come back.
FTE Chapter Leader
Joined: May 2006
Posts: 12,342
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From: Central Mississippi
I'm going to say there is a problem with the 5 vlt reference voltage. Since you have 4 codes that are reading high.
Either something in the wiring or computer.
I had that issue on my truck a few years after converting to MAF, (modded stock harness)
I swapped out to a spare identical computer & got the same batch of codes.
So I pulled an intact & complete MAF harness & swapped it in & codes went away. Obviously something in my hacking of the harness.
Either something in the wiring or computer.
I had that issue on my truck a few years after converting to MAF, (modded stock harness)
I swapped out to a spare identical computer & got the same batch of codes.
So I pulled an intact & complete MAF harness & swapped it in & codes went away. Obviously something in my hacking of the harness.
FTE Legend
Joined: Jun 2006
Posts: 31,930
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From: Ottawa, Ontario
I checked for codes myself prior to sending to the shop and got the following:
Self test Codes:
121 - Closed throttle voltage higher/lower than expected. (Shop has since checked voltage and it is within acceptable range)
334 - EGR closed valve voltage high. (EGR has been deleted)
Continuous memory codes:
113 - Intake air charge temperature sensor above max voltage
118 - Engine coolant temp sensor above max voltage
128 - Manifold absolute pressure sensor failure / vacuum hose disconnected or damaged. (vacuum has since been tested and passed)
542 - Fuel pump secondary circuit fault
Self test Codes:
121 - Closed throttle voltage higher/lower than expected. (Shop has since checked voltage and it is within acceptable range)
334 - EGR closed valve voltage high. (EGR has been deleted)
Continuous memory codes:
113 - Intake air charge temperature sensor above max voltage
118 - Engine coolant temp sensor above max voltage
128 - Manifold absolute pressure sensor failure / vacuum hose disconnected or damaged. (vacuum has since been tested and passed)
542 - Fuel pump secondary circuit fault
Hotshot
Joined: Jun 2015
Posts: 12,872
Likes: 2,445
Installing the smaller BBK twin 56mm throttle body is not going to require any sort of computer tuning. That is the only brand new stock replacement you can buy unless you can find a NOS Ford part. I ran one for years on a stock 302 with absolutely zero problems.
8th Gear
Joined: Apr 2022
Posts: 8
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From: Where ever i'm at.
I had this issue on my 94 E350
Background: I bought a 1994 Ford F150 5.8L V8 351W that has ~190K miles. The previous owner made some upgrades including BBK throttle body and BBK shorty headers and dual exhaust and deleted the EGR valve. Long story short, the truck stalls when coming to a stop when the engine gets to operating temp. There seems to be some sort of hiccup in the engine even when the car is in neutral if the throttle is engaged to low RPMs.
The truck has been in the shop for a while but nothing has been diagnosed. They have gone through a variety of sensor testing that have all come back in spec. My question is - is it possible that the computer is still expecting a reading from the emissions system even though it has been removed? Would that cause the symptoms I am experiencing? I have very little experience with troubleshooting this sort of thing but I'm trying to learn as much as I can and have done quite a bit of research on the issue. I appreciate any and all input!
The truck has been in the shop for a while but nothing has been diagnosed. They have gone through a variety of sensor testing that have all come back in spec. My question is - is it possible that the computer is still expecting a reading from the emissions system even though it has been removed? Would that cause the symptoms I am experiencing? I have very little experience with troubleshooting this sort of thing but I'm trying to learn as much as I can and have done quite a bit of research on the issue. I appreciate any and all input!
Thread Starter
|
Mountain Pass
Joined: Oct 2020
Posts: 112
Likes: 6
I blocked off the egr but left it plugged to the computer to trick it. No longer have that problem. They do have simulators to connect to computer so it thinks its there. I dont know how the delete was done but I would say yes to your comment that computer is still reading/misreading egr.
Thread Starter
|
Mountain Pass
Joined: Oct 2020
Posts: 112
Likes: 6
I'm going to say there is a problem with the 5 vlt reference voltage. Since you have 4 codes that are reading high.
Either something in the wiring or computer.
I had that issue on my truck a few years after converting to MAF, (modded stock harness)
I swapped out to a spare identical computer & got the same batch of codes.
So I pulled an intact & complete MAF harness & swapped it in & codes went away. Obviously something in my hacking of the harness.
Either something in the wiring or computer.
I had that issue on my truck a few years after converting to MAF, (modded stock harness)
I swapped out to a spare identical computer & got the same batch of codes.
So I pulled an intact & complete MAF harness & swapped it in & codes went away. Obviously something in my hacking of the harness.