Accel Gen 7 My experience
06-21-2005, 06:24 PM
#1
Accel Gen 7 My experience I have an ACCEL GEN 7+ and I was having an intermittent MISS problem at higher rpms for over a year. I read a few posts on this board from folks who were experiencing the same sort of problem and also the claims that there is a glitch in the ACCEL GEN 7+.. Nothing could be further from the truth in my case. Here is my experience.
My car had developed an intermittent high rpm miss last year. Car would miss 1 out of 10 passes. I finally called Accel and Craig Smith the Accel/DFI R&D Technician promptly returned my call. I discussed my problem with Craig and we decided to change the spark plug wires back to OEM. Didn't work.
I told Craig I was located only 5 hours away from their shop and I offered my car as R&D to find the problem on their in house dyno. Craig accepted my offer and I brought my car to ACCEL in Feb 2005. I arrived at around 9:30 am and told Craig I also had a hard to start problem. The car was extremely hard to start, especially in the cold Weather. Well, Craig fixed the hard to start problem right away. I drove the car onto the DYNO. The car kept stalling out. We suspected the plugs were fouled but continued to hook the car up to the dyno and diagnostic equipment.
The first pull the car missed badly but the miss was not liken to the problem miss but rather fouled plugs. We changed the plugs and did another pull. NO MISS. We did 8 more pulls to 7,500 rpms and NO MISS. We could not replicate the missing problem. The consensus was that the hard to start problem was glazing the plugs and causing them to prematurely foul. So we think we have found the problem.
We were finished around 8:30 PM and by 9:30 PM I was on my way back home thinking my problem was solved.
At this time I order up a sheet metal intake and new throttle body and install them. I took the car out to 2nd Street Speed and they tuned the car for the new parts. The car made 30 more peak HP and 46 more HP at the big end where my HP used to drop off with the old FAST 78mm intake and 80mm TB. These were not big enough for a 421 stroker motor. Anyway, I'm real pleased with the results. BTW 7500+ RPM on every pull and NO MISS.
I take the car to the track for the first time this year and make my first pass. 9.81 @ 138+ mph and NO MISS. In the pits my car started to idle really high at 4,000 rpms. I checked for the obvious mechanical items that could cause this with NO LUCK. I took the car home and I then found I had sucked an intake gasket in the location where the top portion of the intake bolts onto the lower portion of the intake. I fixed the gasket problem and took the car back to the track on the next TNT night expecting to play with the chassis and suspension parts to net me a better short time. I was WRONG. The 1st pass the car missed bad. Actually worse than before. Made 5 passes and the car missed 4 out of the 5 passes really bad. Worse than ever. I took the car home. The next race was the fist points race. I took the car to the track and I planned to shift early and hope for the best. First TT pass the car missed at the big end just a little and ran a 9.86. The 2nd TT pass the car missed on the 1-2 shift and ran a 9.92. Man I am really bummed out at this time and I dialed in at a 9.92 and hoped the car wouldn't miss. If the car didn't miss I would lift and if it did miss I would run WOT. Well the car missed really bad on the 1-2 shift and again at the big end and ran a 10.00. Needless to say I lost and still had a miss problem that was now much worse.
I now wanted to rule out any possible mechanical problem. Actually I didn't know what to think at this point but I thought this was a good place to start over. I checked the valve lash. It was perfect. Did a leakdown and it also was perfect. I then took the car to a friend of mine who happens to be a professional SBC and BBC engine builder. Tom checked the valve train and all the springs he could reach and said the valve train was CHERRY. I didn't want to pull the heads to check the rest of the springs and Tom said there was no need to at this time. Tom said whomever built this motor is a very good machinist and did a great job. Thanks Judson Massingill and the SAM crew. You build me a fast and reliable bracket motor just like I asked for.
Anyway, Tom said it was in his opinion an ignition problem. Tom said it could possibly be a coil pack breaking down, possibly a bad Cam Position Sensor or something is wrong with the wiring harness or bad ground. I had checked and redid all the grounds previously and I felt confident that wasn't the problem. I decided to swap out the coil packs and change the CPS. I started with the CPS and I took the intake off and noticed the CPS plug was duct taped to the sensor. I then remembered we had to grind off the clip portion of the plug and sensor to get the then new FAST intake to seat properly.
I got to thinking the plug may be moving around causing the problem so I decided to change the CPS plug also. I removed the duct tape off and cut the plug off leaving about 1" of wire still connected to the plug. I inspected the plug closer and found that the green wire was severed with only 1 strand of metal wire holding the wire together. The green wire was damaged about 1/4" from the plug and it was hard to see the damage unless you looked at it really close. I started to jump up and down with great joy. It seems I have found the problem. I called Craig and Judson and they both concurred this was most likely the problem.
I soldered on a new CPS plug and double shrink wrapped all 3 wires. I also installed a new GM CPS. I did not swap out the coil packs at this point.
I took the car back to the track making a total of 9 passes and NO MISS. Saturday June 25 is the next points day and I will see if the car continues to run good.
I want to thank ACCEL for their excellent customer service and for sticking with me throughout this problem. I want to thank Judson Massingill at SAM and Bill and LON at 2nd Street Speed for answering all of my questions and trying to help me out during this ordeal.
Lets go racing,
Tom Staab
My car had developed an intermittent high rpm miss last year. Car would miss 1 out of 10 passes. I finally called Accel and Craig Smith the Accel/DFI R&D Technician promptly returned my call. I discussed my problem with Craig and we decided to change the spark plug wires back to OEM. Didn't work.
I told Craig I was located only 5 hours away from their shop and I offered my car as R&D to find the problem on their in house dyno. Craig accepted my offer and I brought my car to ACCEL in Feb 2005. I arrived at around 9:30 am and told Craig I also had a hard to start problem. The car was extremely hard to start, especially in the cold Weather. Well, Craig fixed the hard to start problem right away. I drove the car onto the DYNO. The car kept stalling out. We suspected the plugs were fouled but continued to hook the car up to the dyno and diagnostic equipment.
The first pull the car missed badly but the miss was not liken to the problem miss but rather fouled plugs. We changed the plugs and did another pull. NO MISS. We did 8 more pulls to 7,500 rpms and NO MISS. We could not replicate the missing problem. The consensus was that the hard to start problem was glazing the plugs and causing them to prematurely foul. So we think we have found the problem.
We were finished around 8:30 PM and by 9:30 PM I was on my way back home thinking my problem was solved.
At this time I order up a sheet metal intake and new throttle body and install them. I took the car out to 2nd Street Speed and they tuned the car for the new parts. The car made 30 more peak HP and 46 more HP at the big end where my HP used to drop off with the old FAST 78mm intake and 80mm TB. These were not big enough for a 421 stroker motor. Anyway, I'm real pleased with the results. BTW 7500+ RPM on every pull and NO MISS.
I take the car to the track for the first time this year and make my first pass. 9.81 @ 138+ mph and NO MISS. In the pits my car started to idle really high at 4,000 rpms. I checked for the obvious mechanical items that could cause this with NO LUCK. I took the car home and I then found I had sucked an intake gasket in the location where the top portion of the intake bolts onto the lower portion of the intake. I fixed the gasket problem and took the car back to the track on the next TNT night expecting to play with the chassis and suspension parts to net me a better short time. I was WRONG. The 1st pass the car missed bad. Actually worse than before. Made 5 passes and the car missed 4 out of the 5 passes really bad. Worse than ever. I took the car home. The next race was the fist points race. I took the car to the track and I planned to shift early and hope for the best. First TT pass the car missed at the big end just a little and ran a 9.86. The 2nd TT pass the car missed on the 1-2 shift and ran a 9.92. Man I am really bummed out at this time and I dialed in at a 9.92 and hoped the car wouldn't miss. If the car didn't miss I would lift and if it did miss I would run WOT. Well the car missed really bad on the 1-2 shift and again at the big end and ran a 10.00. Needless to say I lost and still had a miss problem that was now much worse.
I now wanted to rule out any possible mechanical problem. Actually I didn't know what to think at this point but I thought this was a good place to start over. I checked the valve lash. It was perfect. Did a leakdown and it also was perfect. I then took the car to a friend of mine who happens to be a professional SBC and BBC engine builder. Tom checked the valve train and all the springs he could reach and said the valve train was CHERRY. I didn't want to pull the heads to check the rest of the springs and Tom said there was no need to at this time. Tom said whomever built this motor is a very good machinist and did a great job. Thanks Judson Massingill and the SAM crew. You build me a fast and reliable bracket motor just like I asked for.
Anyway, Tom said it was in his opinion an ignition problem. Tom said it could possibly be a coil pack breaking down, possibly a bad Cam Position Sensor or something is wrong with the wiring harness or bad ground. I had checked and redid all the grounds previously and I felt confident that wasn't the problem. I decided to swap out the coil packs and change the CPS. I started with the CPS and I took the intake off and noticed the CPS plug was duct taped to the sensor. I then remembered we had to grind off the clip portion of the plug and sensor to get the then new FAST intake to seat properly.
I got to thinking the plug may be moving around causing the problem so I decided to change the CPS plug also. I removed the duct tape off and cut the plug off leaving about 1" of wire still connected to the plug. I inspected the plug closer and found that the green wire was severed with only 1 strand of metal wire holding the wire together. The green wire was damaged about 1/4" from the plug and it was hard to see the damage unless you looked at it really close. I started to jump up and down with great joy. It seems I have found the problem. I called Craig and Judson and they both concurred this was most likely the problem.
I soldered on a new CPS plug and double shrink wrapped all 3 wires. I also installed a new GM CPS. I did not swap out the coil packs at this point.
I took the car back to the track making a total of 9 passes and NO MISS. Saturday June 25 is the next points day and I will see if the car continues to run good.
I want to thank ACCEL for their excellent customer service and for sticking with me throughout this problem. I want to thank Judson Massingill at SAM and Bill and LON at 2nd Street Speed for answering all of my questions and trying to help me out during this ordeal.
Lets go racing,
Tom Staab
I ran a 9.82 @ 138.XX on this pass.
07-17-2005, 08:37 AM
#5
On The Tree
Join Date: Dec 2003
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let me get this straight,accel could not find the problem.so when you finally did the tech squad at accel said,hey thats it!sounds like another problem solved by accel!these guys crack me up. 
