hineas
01-05-2024, 07:59 AM
I haven't posted in a while, but I wanted to share some issues we had in case it helps someone else on the thread.
My brother and I build the car together, and we have the BluePrint 347 with the Holley Sniper EFI in our Mk4 Roadster. We have about 7,500 miles on the car. Overall, we have thoroughly enjoyed the car.
We have, however, had some issues with the engine not running perfetly. The issues were sporadic, which makes chasing it down difficult. Sometimes the engine would stutter with more than gentle acceleration. After it would stutter then it would take off. Sometimes there wouldn't be a stutter but the engine would surge during acceleration. Sometimes we had issues with the idle, especially when pulling up to a stop sign it would drop to 400-500 rpm and almost die, but then it would idle. Occasionally the engine would die when I would pull into a stop sign. Sometimes the car would surge cruising at 75 mph with the cruise control on, but when I turned off the cruise control it would still surge. Sometimes I had less power and had to down shift to go up hills while other times I go up any hill in 5th gear. I also noticed that the fuel efficiency was slightly worsening (maybe 1-2 mpg less than when we first started driving the car). We were getting 20-22 mpg on the highway, and now we were getting 18-20.
At first these issues were occasional, but it slowly got more and more frequent. It was frustrating.
We first thought we didn't have the IAC adjust well (that would at least explain the issues with the idle). We adjusted it and dialed it in where we wanted but it made no difference.
I thought about checking the spark plugs to see if any were fouled, but the issue was sporadic and it didn't feel like a misfire so we decided to check other issues first.
We thought it was an issue with the auto-learning and the basic tune. We played with the settings. We found that if we changed it to run a little more rich it would help somewhat, but it still didn't fix the issue.
We hired a guy to help us with the tune remotely. He looked at our fuel map and said that there were places were the EFI was adding 40-50% more fuel than expected. He said that when he sees that it is usually a fuel delivery issue. He said we needed to figure out the fuel delivery issue before we could do a tune.
I ended up adding a fuel pressure gauge to the line. I ran the line for the gauge into the cab so I could watch it real-time while driving. The pressure never budged from 60 psi even under hard acceleration. When it stuttered and surged the pressure stayed at 60 psi. We had wondered if the fuel filter was clogged, but with constant pressure even under hard acceleration we figured that wasn't the issue.
One drive was particularly bad. It died on me 3 times downshifting on a mountain road and I would pop the clutch to get the engine running again. It died at 2 stop lights. It had no power whatsoever, and I had to downshift to 3rd gear to go up hills that I could usually go up in 5th gear. During all of these issues the fuel pressure stayed at a constant 60 psi. This was on the Million Dollar Highway in Colorado and should have been an amazing drive, but it was the most disappointing drive ever. At least the scenery was good! Here's my obligatory picture of the car on that drive
194128
At this point we had narrowed down the issue to the EFI system itself. Fuel was being delivered to the EFI but the fuel map suggested it wasn't getting enough fuel. I did a bunch of research on the Holley forums. I found that many people had similar issues and the pressure regulator in the Holley Sniper isn't great and can fail. One guy had an issue with his regular that made it fail intermittently. We pulled out the pressure regulator and it looked fine, but we ended up replacing it since we took it out (it was maybe $20). That didn't help.
I scratched my head and did more research. I started looking up issues with the fuel injectors, and one guy had the exact same intermittent issues as us. He said that he found that the electrical connection to the fuel injector wasn't a great design and it was causing his issue. He said the clip that holds the plug together wasn't strong enough and it would lift off and loosen over time. He fixed it with a zip tie around the connection to hold the clip in place.
We pulled off the air filter and looked down into the barrels of the EFI with the engine running. Only 3 of the 4 barrels had gas in it and the other was dry. Sure enough, the issue had to be one of the fuel injectors.
We took apart the fuel injectors. One of the connections was indeed loose. Also, the way the connector is made, the female and male ends of the pins on either side can move inside the connector. It looked like when the plug was connected from the factory the male end didn't go into the female end and was just pushed against the side of the pin. This is probably why it caused intermittent issues.
We checked all of the connections, and 2 out of 4 fuel injectors had the issue but the 2nd wasn't as bad as the first. We made sure the pins lined up perfectly when we connected the plug. Next, we put a small zip tie snugly around the connector to hold the locking clip in place. Sure enough, after doing this we could see gas being delivered into all 4 barrels of the EFI. Huzzah!
We have put about 400 miles on the car since we fixed the injector issue. We haven't had a SINGLE stutter and no surging. There have been no issues with the idle dropping to low rpms at stop signs. We haven't seen any issues with the engine dying when down shifting. I can once again go up any hill in 5th gear with ease. In fact, the car has more power than it ever did (and the car could still break the tires loose in the blink of an eye before we fixed the issue). I did a few hundred mile drive this week and it was, hands down, the most enjoyable drive I have ever had in the car. It worked flawlessly.
Looking back, I can see that the electrical connector was likely slowly loosening the more we drove it. That is why our issue was almost non-existent when we first built the car but became unbearable after 7,000 miles.
Hopefully this helps others in the future!
My brother and I build the car together, and we have the BluePrint 347 with the Holley Sniper EFI in our Mk4 Roadster. We have about 7,500 miles on the car. Overall, we have thoroughly enjoyed the car.
We have, however, had some issues with the engine not running perfetly. The issues were sporadic, which makes chasing it down difficult. Sometimes the engine would stutter with more than gentle acceleration. After it would stutter then it would take off. Sometimes there wouldn't be a stutter but the engine would surge during acceleration. Sometimes we had issues with the idle, especially when pulling up to a stop sign it would drop to 400-500 rpm and almost die, but then it would idle. Occasionally the engine would die when I would pull into a stop sign. Sometimes the car would surge cruising at 75 mph with the cruise control on, but when I turned off the cruise control it would still surge. Sometimes I had less power and had to down shift to go up hills while other times I go up any hill in 5th gear. I also noticed that the fuel efficiency was slightly worsening (maybe 1-2 mpg less than when we first started driving the car). We were getting 20-22 mpg on the highway, and now we were getting 18-20.
At first these issues were occasional, but it slowly got more and more frequent. It was frustrating.
We first thought we didn't have the IAC adjust well (that would at least explain the issues with the idle). We adjusted it and dialed it in where we wanted but it made no difference.
I thought about checking the spark plugs to see if any were fouled, but the issue was sporadic and it didn't feel like a misfire so we decided to check other issues first.
We thought it was an issue with the auto-learning and the basic tune. We played with the settings. We found that if we changed it to run a little more rich it would help somewhat, but it still didn't fix the issue.
We hired a guy to help us with the tune remotely. He looked at our fuel map and said that there were places were the EFI was adding 40-50% more fuel than expected. He said that when he sees that it is usually a fuel delivery issue. He said we needed to figure out the fuel delivery issue before we could do a tune.
I ended up adding a fuel pressure gauge to the line. I ran the line for the gauge into the cab so I could watch it real-time while driving. The pressure never budged from 60 psi even under hard acceleration. When it stuttered and surged the pressure stayed at 60 psi. We had wondered if the fuel filter was clogged, but with constant pressure even under hard acceleration we figured that wasn't the issue.
One drive was particularly bad. It died on me 3 times downshifting on a mountain road and I would pop the clutch to get the engine running again. It died at 2 stop lights. It had no power whatsoever, and I had to downshift to 3rd gear to go up hills that I could usually go up in 5th gear. During all of these issues the fuel pressure stayed at a constant 60 psi. This was on the Million Dollar Highway in Colorado and should have been an amazing drive, but it was the most disappointing drive ever. At least the scenery was good! Here's my obligatory picture of the car on that drive
194128
At this point we had narrowed down the issue to the EFI system itself. Fuel was being delivered to the EFI but the fuel map suggested it wasn't getting enough fuel. I did a bunch of research on the Holley forums. I found that many people had similar issues and the pressure regulator in the Holley Sniper isn't great and can fail. One guy had an issue with his regular that made it fail intermittently. We pulled out the pressure regulator and it looked fine, but we ended up replacing it since we took it out (it was maybe $20). That didn't help.
I scratched my head and did more research. I started looking up issues with the fuel injectors, and one guy had the exact same intermittent issues as us. He said that he found that the electrical connection to the fuel injector wasn't a great design and it was causing his issue. He said the clip that holds the plug together wasn't strong enough and it would lift off and loosen over time. He fixed it with a zip tie around the connection to hold the clip in place.
We pulled off the air filter and looked down into the barrels of the EFI with the engine running. Only 3 of the 4 barrels had gas in it and the other was dry. Sure enough, the issue had to be one of the fuel injectors.
We took apart the fuel injectors. One of the connections was indeed loose. Also, the way the connector is made, the female and male ends of the pins on either side can move inside the connector. It looked like when the plug was connected from the factory the male end didn't go into the female end and was just pushed against the side of the pin. This is probably why it caused intermittent issues.
We checked all of the connections, and 2 out of 4 fuel injectors had the issue but the 2nd wasn't as bad as the first. We made sure the pins lined up perfectly when we connected the plug. Next, we put a small zip tie snugly around the connector to hold the locking clip in place. Sure enough, after doing this we could see gas being delivered into all 4 barrels of the EFI. Huzzah!
We have put about 400 miles on the car since we fixed the injector issue. We haven't had a SINGLE stutter and no surging. There have been no issues with the idle dropping to low rpms at stop signs. We haven't seen any issues with the engine dying when down shifting. I can once again go up any hill in 5th gear with ease. In fact, the car has more power than it ever did (and the car could still break the tires loose in the blink of an eye before we fixed the issue). I did a few hundred mile drive this week and it was, hands down, the most enjoyable drive I have ever had in the car. It worked flawlessly.
Looking back, I can see that the electrical connector was likely slowly loosening the more we drove it. That is why our issue was almost non-existent when we first built the car but became unbearable after 7,000 miles.
Hopefully this helps others in the future!