A couple of years ago my 99 5.7 was hard to start and would exhibit sort of a small backfire under the hood. I was advised to upgrade to MFI, which I did. I thought that was going to be a permanent solution but now I'm having the symptoms all over again. :-( What gives?
MFI fail
- Thread starter bldn10
- Start date
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SunlitComet
OBS Jedi-Do Good
any active or stored codes in the pcm?
SunlitComet
OBS Jedi-Do Good
was this stored codes as well? would recommend you get some basic checks done first such as spark on the cylinders and fuel pressure. and you are saying at the moment it will not even try to fire or it is doing the backfire while trying to start? please give as much detail as possible. no matter how odd it sounds.
No codes. Its getting fire. I always wait until the fuel pump stops before starting, and there is gas in the bowl. The backfire (frontfire?) occurs sporadically during cranking. It will sorta diesel a bit after turning the key off. This is all exactly what it did before I changed out the spider.
It finally started yesterday after prolonged cranking and, as is usual, then started right up each time after that. Symptomatic of leaking injectors washing down the cylinders causing insufficient compression?
It finally started yesterday after prolonged cranking and, as is usual, then started right up each time after that. Symptomatic of leaking injectors washing down the cylinders causing insufficient compression?
SunlitComet
OBS Jedi-Do Good
gas in the bowl? well anyways there are several things to look at unfortunately you would need a much more capable scanner or shop help. one id=s to check the output of crank sensor for anomalies. actually if you have a scanner that can read your rpm then that is good. you will want to compare the reading to the reading on the tachometer. are they the same? the other is a injector balance test. this would involve a scanner and fuel pressure testing to determine if the injectors are passing the right amount of fuel on each cylinder in a test mode. you can open the throttle body and ses if you get a strong smell of gas after shutdown. have you tested your compression? do you actually have some low readings? and the first time you thought you solved it it was strictly the spider and regulator that was replaced correct? no other sensors at all?
