Topic: Backfiring/stalling

[sharpxmen]

Guess I will pick up a timing light and voltmeter on my way to work today... Have a jeep I bought solely for parts that I am probably going to take the TPS off of see if that is the problem.. I haven't taken the distributor off since I replaced the coil so i hadn't really thought to mess with it. I didn't think I could adjust the timing from there though so it is definitely worth a look too.

you can't adjust timing from the distributor, but you can be a tooth off which would make the rotor and the cap prongs to be not aligned, if you didn't touch it i would not mess with it. The reason i mentioned the timing was to check what the hell is going on with the map sensor disconnected - but you could start with the voltages and the fuel pressure and go from there, if you need the voltage levels i can dig them out of the FSM.

[Jeffy]

Guess I will pick up a timing light and voltmeter on my way to work today... Have a jeep I bought solely for parts that I am probably going to take the TPS off of see if that is the problem.. I haven't taken the distributor off since I replaced the coil so i hadn't really thought to mess with it. I didn't think I could adjust the timing from there though so it is definitely worth a look too.

The distributor is either in on 180* out.  That's all you get.  Everything else is PCM controlled through the CPS.

[sharpxmen]

The distributor is either in on 180* out.  That's all you get.  Everything else is PCM controlled through the CPS.

you can go 1 tooth or more off, the oil pump moves freely so you can rotate that whichever way you want (should lineup with the distributor gear but won't keep you from missing the mark). Anyway, since he didn't touch it it's not an issue.

[Jeffy]

you can go 1 tooth or more off, the oil pump moves freely so you can rotate that whichever way you want (should lineup with the distributor gear but won't keep you from missing the mark). Anyway, since he didn't touch it it's not an issue.

The PCM is able to adjust for those minor differences though.

[sharpxmen]

The PCM is able to adjust for those minor differences though.

timing is the same, there's nothing to adjust by the PCM when you're out a tooth at the distributor gear since the spark is based on the crank sensor signal and not the cam signal in the distributor (this one is used for injector opening sequence). the problem is when the spark occurs the rotor is not in line with the prong inside the cap, so to try and explain a little better - think when the crank rotates and the spark fires for cyl 1 at (for the sake of argument) 20 deg before tdc and the rotor is in line with the prong for cyl 1 - now, if the dist gear is off 1 tooth the spark will still occur at the same rotational position of the crank (20 deg since it's all based on the crank sensor) but the metal at the end of the rotor will be away from the cyl 1 prong by some distance and not lined up, you lose spark there, might still run but the spark would be weak or missing.

that's what i was trying to say in my initial post abou this.

[sharpxmen]

i remember now seeing a post where it would start and stop immediately due to the cam and crank sensor being out a tooth and the PCM was throwing an error, so the whole thing premise i started with might not even work in real life scenario, anyway i'm going off-topic here.

[TexWalther]

Due to lack of tools for checking fuel pressure, voltages, timing, or compression I gave in and took it to a shop.. turns out the fuel pump I installed a few months ago was garbage. Autozone replaced it and all I got stuck with was the labor so didnt end up being to bad.. Thanks for all the help and input though

[sharpxmen]

Autozone sells garbage, i would check rockauto or amazon for brand parts next time.

[Jeffy]

Autozone sells garbage, i would check rockauto or amazon for brand parts next time.

Most auto parts chains get their parts from the same third-party mfg. that Mopar gets theirs from.  Also, not having to ship parts back and forth compared to in-stock local parts store is a huge advantage.

[sharpxmen]

my thinking is you buy a Bendix rather than a store brand fuel pump for example, 20 or 30 bucks more but better quality, it less likely to have a DOA pump. With Amazon you get free shipping back and forth if the part is faulty or wrong to get a replacement.

[chardrc]

usually at the autoparts store there are 2 or 3 options. so you can buy the garbage that dies in a year or the quality stuff that will last. I've only been to an auto-zone a handful of times so can't speak for them but o'rielly is good if you can find an employee that knows what they are doing or when to get out of the way.

[Jeffy]

my thinking is you buy a Bendix rather than a store brand fuel pump for example, 20 or 30 bucks more but better quality, it less likely to have a DOA pump. With Amazon you get free shipping back and forth if the part is faulty or wrong to get a replacement.

That's still a week wasted unless you but two and get credited back.  I've bought a bunch of parts from Amazon and with Prime it's nice since I can get one-day shipping for a few bucks more.  Because of their weird pricing, you can sometimes find really good deals as well.  Like Chardrc said, you typically get a few options at the LPS.  If the price difference is small, then it's a no brainer.  I used to shop O'rielly's but I go to Napa now as there is one in town.  They can get parts my 11am if they don't have it in stock and I call in early.  Not to mention the old guy there recognizes me and the store has been in that location for what seems forever.

[sharpxmen]

i got platinum plugs for $2.50 at amazon that were quoted $8 at Napa (same brand), same for plug wires $25 at Amazon and $63 at Napa, I can go on. Where you actually get the same deal or better at Napa or other stores like that is on private labels or things that don't get sold as much, at least where i'm at not sure in California. There is the odd time when i need it "now" and go to the LPS, nothing you can do about that. Thing is that if you replace the pump or anything else that is not easily accessible it sucks to do the work (or pay for it) twice, if it's something easily accessible no brainer. I got stuck on the hwy once with an ignition coil that failed after 2 months, bought an MSD oem replacement next and it's been running fine ever since. My prime membership has paid itself over a few times if not more, can't beat 2 day free shipping