Spyder P1105 code and backfiring issue

[tatan_Dsm97]

I have a backfiring issue with my 97 Spyder Gst. It does not have any modifications done recently, it was running fine until one day the Check Engine light came up and when I checked it it showed the P1105 code. However, I did not replace anything and just disconnected the battery to erase the code and see if it came up again. Now, it came up again, I researched and it said it was something malfunctionning with fuel pressure solenoid. So I replaced the fuel pressure regulator thinking that was the problem because the FPS looks ok. My car seems like misfiring when I am starting to get up to speed and when I start boosting it sputters very bad. However, when I am crusing maintaining the same speed/accelaration it does not backfire (or misfire) The misfiring is not present in the 2k-3k rpms range unless I step on it
Sometimes when I start it, the engine vibrates and seems like one of the cylinders is not firing properly, but as soon as I step a litle on the gas it goes back to normal and evens.
When I replaced the FPR it seemed to work a lil better when getting up to speed but still backfires a little and when I step on it it still sputters when boosting.

What if I run the vacum hose directly from the FPR to the intake manifold skipping the solenoid?
What are the differen things that might be causing the car to act like this?

 

[synthetek]

What if I run the vacum hose directly from the FPR to the intake manifold skipping the solenoid?

It is ok to run it like that. It may not be the cause of your problem but it wont hurt to try.

 

[luv2rallye]

The ECU has determined the fuel pressure solenoid has an open or short in it or it's wiring. The FPS raises fuel pressure on warm starts to reduce vapor lock for easier starting. Sounds like that is your problem - replace it.

 

[tatan_Dsm97]

Ok, I am trying the connection of the vacum hose directly to the FPR, however, I still get some backfiring and when boosting it still sputters.

What are the causes for the sputtering? Backfiring?

 

[tatan_Dsm97]

Ok, I tried disconnecting the vacum hoses from the FPS and connected the FPR vacum hose directly to the intake manifold nipple and reset my ECU. the code dissapeared and did not come back for the period I had the FPR connected directly to the intake. However, one day I went and cleaned the Fuel pressure solenoid and reconnected everything like it was supposed to be and the code did not appear for a few weeks but now I got it again, so I guess my FPS is bad and does need replacement.

As for the misfiring and sputtering problem, I found a major vacum leak by my BOV and also the gap in my spark plugs were too big so I went and got new ones and spaced them correctly to 0.030 and it immediately fixed the sputtering problem. At idle I was still getting some misfiring so I went to look at my cables and coils and discovered the coil for cylinder 1 was missing part of the plastic where the cable connects. Also, the connections for that cable (both at the coil and the spark plug) were of different color than the connections for the other cables.

I got new coils and a set of NGK blue cables and this was the solution for my misfire.

Thanks for your input on the FPS problem I had.