Before I get into the details...mod list:

60lb injectors
dual pass + option b
zzp tune
zzp headers/downpipe + aftermarket muffler
2.8 pulley
mounts
ngk step 2 colder plugs
and many others, but that's what should be relevant to this post.

Basically the past 3-4 months I've had some starting issues, and some odd "hesitation" issues. To me, it seems fuel related, but I wanted to get others opinions. Basically 80% of the time when I go to start the car, it has problems starting. It'll crank for 3-4 seconds, sometimes as long as 5-7 before starting, and then it sounds like it's starved for fuel for a second or two before the idle normalizes. This happens when it's hot/cold/day/night...it's random. If I turn the key to "acc", I can hear the pump kick on -- it's not exactly LOUD, but it's not like I pay attention to it every time I start the stupid thing. To try and help the problem, I've seafoamed the car and replaced the filter. I don't remember how "dirty" the filter looked (I saw another post regarding the filter causing the pump to go bad)....but I'm sure the original owner has never changed it and I have 73k miles on it. I've had a problem with boost not going over 14psi ever since I did all my mods, but I thought it was just because I'm running 60lb and the 2.8 pulley. ZZP confirmed they don't put any boost limits on the 2006 model year tunes. Again, this could be normal with the mods.

My question -- other than "odd" noises, how else can I test the fuel pump to rule that it is the problem? I have an aeroforce guage, will any of the gauges hint of the problem? My fuel trims bounce around, but they have ever since I installed everything. I have 60lb injectors, so my idle isn't going to be "smooth" anyways. I was hoping other than removing the tank to get to it, there was an easier way to diagnose the problem.

Any suggestions?

 

I've been having the same startup problem with my car, but mine only does it on cold starts. It'll do it when I start it to drive to the store, but not on the way back. I tried messing around with the fuel on startup tables in my tune with no effect. I'm going to clean out the throttle body and IAC butterfly later today on the off chance that's causing it.

The hesitation issues - you mean like if you stab at the gas in low gear it sorta hesitates a sec before it goes? That's usually caused by a rich tune.

 

Mine used to do it only on cold starts (if it sat for longer than 12 hours or so). But recently it started doing it even on warm starts (car has sat for less than 12 hours). I'm going to try and get some video of it.

The hesitation is odd too -- I was testing something out, was WOT in second gear and in high RPM's (~6k) it just bucked for a split second and took off again....it was the weirdest thing. It was almost like knock....but I wasn't monitoring for knock at the time so I didn't see anything. It hasn't done it again, but I also haven't been running it hard in fear of my fuel pump being on its last legs. I do however notice a very slight buck when I am in low rpm's 1.8-2k in traffic if I'm holding steady gas. That could just be me imagining things since I THINK I have a fuel pump problem. I don't have tuning software to grab data, so I can't prove it. I've also felt like 3rd gear pulls (not racing) seem sluggish. Again, could be because in my head I think I have a problem.

I did clean the throttle body last year. I was thinking this weekend I'll take out and inspect the plugs and also clean the MAF since my filter needs cleaning anyways.

I HAVE been monitoring for knock the past couple of days and haven't had any.

I may try to let the fuel pump run for a few seconds before actually starting the car to see if this helps. I'll try anything before taking it in.....they'll charge an arm and an leg to try and troubleshoot something like this. Including replacing numerous parts they THINK is the problem.

 

I have the same problem. I have to hold the key for 5-7 sec to start the car when it is cold. I have tried turning the key on/off/on then starting and it doesnt change. When the car is hot and sitting for less than 45ish mins it will start right up.

Has been doing this for about a year. From what I remember it started when I switched pcm's trying to fix a tps code but has continued to do it even when I switched the pcm a second time cause I had an 06 in a 05 car.


I have only felt a "stumble" once and it was at full throttle at high rpm. I attributed it to a possible misfire/knock from high iat2.

 

So far mine's only doing it on cold starts. Last night it actually stumbled so bad it stalled out.

I'd suggest cleaning your MAF and checking the gap on your plugs. That's usually either knock, a misfire or a spark blowout (depending how large you gap your plugs). If you generally don't see knock it's probably just a misfire.

If you're bucking in low RPM that's usually either a sticky TB or a rich tune. Mine would buck on shifting when my VE table was too high.

I'm doing the same. When I started it up to head to the movies this morning (after leaving the key on for 5-10 secs) it still stumbled a little but not nearly as bad as it was. I'm gonna clean the TB really well before I go to bed tonight.

 

well....tonight i started screwing around with my interceptor when low and behold, i checked the dtc codes and i had like 10 of them! i decided to erase them and i'll drive it around tomorrow and see if any come back. i noticed that good ole p0315 came right back. i'm going to try the relearn with the aeroforce tomorrow and see if i can get rid of that. i'm almost wondering if that's my problem, although WOT it still pulls pretty damn hard.

plugs and MAF will get looked at this weekend. i'll keep this thread updated.

p.s. i have the zzp custom tuned PCM.....i found it odd my check engine light didn't come on with at least ONE of those f'ing codes. i'm hoping they were all just old codes. we'll soon find out!

sorry for grammer/english/typos....too tired to press shift key or backspace

 

From my experience if the interceptor pics up codes but the CEL isn't on, it generally means that they're immature (the system picked it up enough times to take note, but not enough to throw the CEL).

I went out tonight and pulled the TB off and gave it a good wipe down with carb cleaner, then fired it up without waiting for the fuel pump to prime. It didn't sputter at all, but I'll keep an eye on it just to see if it was a coincidence (or if I hadn't let it sit long enough).

 

I think this is something to bring up to Aeroforce and ask directly. Seems odd to me and makes me wonder if it's disabling the check engine light for certain codes. I may check their forums later today for answers.

I cleaned my TB last year. She wasn't even dirty, but I decided to do it anyways so I'm not 100% that's going to be my fix. But it won't hurt to do it while I have the air filter out anyways.

 

It wouldn't be the Interceptor at fault, it would be the ECU. Depending on the code it's normal for it to get saved but not throw a CEL (mine would display a rich condition code for a couple days before it would actually kick the light on, same thing with the P0300 misfire code)

 

Funny -- today the interceptor had a p0300 code stored in it, but not CEL. So this is normal?

I need to just find the damn 5 minutes to pull my plugs and inspect them. I'm going to guess this is where my problems are coming from. I'm hoping I don't have any internals going on me.....of course it WOULD be the excuse to tell my wife that it's time for me to do my complete engine overhaul and make the damn thing a beast.

I'm going to email ZZP and see if they blocked these codes from throwing CEL, and if so, if my interceptor's codes can be ignored.

 

I used to get the p0300 code all of the time when I was completely stock. The only reason I knew it was there was cause I saw it on the interceptor.

p0300 never threw a cel in my car even if it was in the memory

 

Same, mine would always have the P0300 in the interceptor but no CEL until I changed my fuel maps, then it went away for good. Then again, when I put the new fuel map on that's when this started. Might flash back to my old tune to see if it goes away or it's just a coincidence.

 

I've been giving the car 10 seconds to prime the pump before starting it, and still stumbles on startup. Looks like my issue isn't fuel system related. Going to try flashing the old fuel table back to see if that helps.

 

Put the old tune back on the car, doesn't seem to be fuel table related. I'm gonna try some injector cleaner to see if that helps any.

 

You might want to try 1 step plugs instead of 2. Might not be getting a hot enough spark to burn all the fuel properly. 2 step is not needed with a 2.8. There probably doing more harm than good.

 

I am running bkr7e at ??? gap.

 

Same. I'm starting to think it's the summer gas, pretty sure they just started using it around here.

 

Sorry for not checking in. I checked my gap, was at .40....not sure how, I reset them to .33 where I originally had them. No change. I cleaned the MAF. Nothing. Who knows. I'm just going to give up. I may play with the gaps some more cause after changing them to .33 I think I have a few weird issues. If it fixes the original issue, I'll post and let people know.