Need help please, new motor, now pings bad
Posted: August 1st, 2012, 8:20 am
Hello all,
This is my first post, been surfing the site for a while now, great info. Sorry for such a long first post, but I need some help getting a freshly rebuilt 258 to run correctly.
I had my 1987 258 4.2 with junk yard MPFI blow up last fall, #2 piston broke apart. The motor had over 100,000 miles on it. I found a different 87 block and had it professionally rebuilt. The motor was bored .030 over, with stock pistons, a comp cam Xtreme 4x4 X4250H-13. I am running a 4.0 head, the head was milled flat, nothing more, as was the top of the block, not sure how much the block was taken down. I run a stock 4.0 MPFI junk yard obtained fuel injection. The compression ratio was raised to around 9.7-9.8 per the engine builder. The motor was broke in correctly to break in the cam and such. While breaking in the cam, the exhaust system got red hot all the way to the muffler, not sure why as it has not done this since. The motor however never runs over the normal temp, no overheat condition. When driving the motor pings at mid throttle. If I keep the jeep in neutral and rev up the motor it makes a strange noise at around 2000 rpms. The engine builder seems to think it is the ping as it sounds like it is in the exhaust manifold. The engine builder checked the compression of each cylinder, this is what they are:
1-181
2-183
3-180
4-181
5-179
6-183
I am stumped, as I do not know where to go from here. The engine builder is a reputable local builder, he knows how to build a good motor, but he knows nothing about the MPFI. I am running stock MPFI components from the junk yard. I had these components on the stock motor for 3 years with no problems before the motor let go last fall. The motor was tired, I knew that.
The motor builder spoke with Comp when choosing the cam and it was recommended by Comp. We checked the plugs, they are very clean and look new, it is clearly running lean. The plugs are almost white. I am running fresh 91 octane gas. The motor pings quite badly. I am afraid to drive it and have not done so. The motor runs very smooth, just has major pinging at moderate throttle. I am running a cold air intake with an open element air filter. I am running the spark plugs recommended by Hesco with their MPFI kit, they are champion RC9YC I believe. I am using the single line fuel injection from a 95 4.0. The fuel pressure while at idle is about 50 psi, and is about 46-47 psi while at hard throttle application while driving. The injectors are stock and are probably the original stock injectors from 1995. The timing was checked and found to be about 12 degrees at idle if I remember correctly, per hesco this is correct?
Is there a way to see the timing and what it is doing using a mopar scan tool? Can the timing be adjusted using the scan tool? It would be interesting to see what timing is doing while driving. I was unable to figure out why my last motor blew up, wondering if it was running lean as well the whole time and finally let go after 3 years. I do not however put many miles on per year, about 3-4,000.
I am stumped, the wife is pissed as I spent a fair amount of money on the motor, and we cannot drive the Jeep and it sits in the garage. Please help me get this thing running correctly and strong. I feel the motor was built well and should have great power, it just needs to be tuned correctly, but I am not quite sure how to do that.
I was told to obtain a wide band 02 sensor and check the air/fuel mix, I am working on finding one at the moment. Where do I go from here?
This is my first post, been surfing the site for a while now, great info. Sorry for such a long first post, but I need some help getting a freshly rebuilt 258 to run correctly.
I had my 1987 258 4.2 with junk yard MPFI blow up last fall, #2 piston broke apart. The motor had over 100,000 miles on it. I found a different 87 block and had it professionally rebuilt. The motor was bored .030 over, with stock pistons, a comp cam Xtreme 4x4 X4250H-13. I am running a 4.0 head, the head was milled flat, nothing more, as was the top of the block, not sure how much the block was taken down. I run a stock 4.0 MPFI junk yard obtained fuel injection. The compression ratio was raised to around 9.7-9.8 per the engine builder. The motor was broke in correctly to break in the cam and such. While breaking in the cam, the exhaust system got red hot all the way to the muffler, not sure why as it has not done this since. The motor however never runs over the normal temp, no overheat condition. When driving the motor pings at mid throttle. If I keep the jeep in neutral and rev up the motor it makes a strange noise at around 2000 rpms. The engine builder seems to think it is the ping as it sounds like it is in the exhaust manifold. The engine builder checked the compression of each cylinder, this is what they are:
1-181
2-183
3-180
4-181
5-179
6-183
I am stumped, as I do not know where to go from here. The engine builder is a reputable local builder, he knows how to build a good motor, but he knows nothing about the MPFI. I am running stock MPFI components from the junk yard. I had these components on the stock motor for 3 years with no problems before the motor let go last fall. The motor was tired, I knew that.
The motor builder spoke with Comp when choosing the cam and it was recommended by Comp. We checked the plugs, they are very clean and look new, it is clearly running lean. The plugs are almost white. I am running fresh 91 octane gas. The motor pings quite badly. I am afraid to drive it and have not done so. The motor runs very smooth, just has major pinging at moderate throttle. I am running a cold air intake with an open element air filter. I am running the spark plugs recommended by Hesco with their MPFI kit, they are champion RC9YC I believe. I am using the single line fuel injection from a 95 4.0. The fuel pressure while at idle is about 50 psi, and is about 46-47 psi while at hard throttle application while driving. The injectors are stock and are probably the original stock injectors from 1995. The timing was checked and found to be about 12 degrees at idle if I remember correctly, per hesco this is correct?
Is there a way to see the timing and what it is doing using a mopar scan tool? Can the timing be adjusted using the scan tool? It would be interesting to see what timing is doing while driving. I was unable to figure out why my last motor blew up, wondering if it was running lean as well the whole time and finally let go after 3 years. I do not however put many miles on per year, about 3-4,000.
I am stumped, the wife is pissed as I spent a fair amount of money on the motor, and we cannot drive the Jeep and it sits in the garage. Please help me get this thing running correctly and strong. I feel the motor was built well and should have great power, it just needs to be tuned correctly, but I am not quite sure how to do that.
I was told to obtain a wide band 02 sensor and check the air/fuel mix, I am working on finding one at the moment. Where do I go from here?