Intermittent "hiccup" While Driving

Mattstang04

15 Year Member
Sep 15, 2006
1,152
143
104
St. Louis, MO
I have a mystery issue. Sometimes I'll just be cruising at a steady speed, sometimes I'm accelerating but my engine seems like a switch is flipped on and off. Killing it completely for a millisecond, just long enough to make the car do a single buck before carrying on like nothing happened.

The problem started in the year after I put my blower on. It usually happens after the car is warmed up and is cruising at a consistent speed. There have been a handful of times that it happened while I was accelerating aggressively. It doesn't happen every time I drive the car.

My list of "could be's" include blower belt slip, because I'm not sure how that feels, a fuel pump issue, an ignition failure of some sort, or a tune issue. I really have no idea what it could be.

Anybody ever had anything like this happen to them?
 
  • Sponsors (?)


Hmm, how long has the blower been on? Belt slip sounds like a possible cause. How long has that belt been on there? Also your spark plug gap. What are they gapped at? If your plugs are at the OEM gap then you need to get in there and close it a little. I think I went with 0.30-0.35. Another thing to check is your BOV. Sometimes they weaken and let a little boost out. I was running the Bosch BOV but then I changed it to a better more heavy duty one. Those three things could all be possible problems. If it has been happening ever since the blower was installed then I'm leaning towards thinking that the BOV or spark plug gap is the cause of your woes...lol.
 
The Procharger has been on there for about 3 years. I put colder NGK plugs in it. I think I set the gap at .31. It has the original belt that Procharger sent with the kit. Still using the Procharger BOV as well. Probably have just under 20k on the whole setup.

I have a boost gauge on the car but the problem occurs so intermittently and quickly that I'm never looking at the gauge when it happens.

What else can you tell me about BOVs? A Google search revealed some rather negative feedback about Procharger's supplied unit. Whats a good replacement piece? Where can I get one?
 
Last edited:
Save your self a possible wild goose chase and start by having the battery and alternator tested.

Are the battery terminals clean and tight? Start this trouble shooting with a known good charging system.

Bottom line. Today's cars simply will not run right without a strong battery and charging system.

THEN consider getting an "add a fuse" for the Central Junction Box (CJB) fuse F2.8. The "add a fuse" will make it possible to easily monitor the F2.8 circuit with a Volt-Ohm Meter (VOM). What we are looking to rule in/out is if the voltage is dropping when the problem occurs.

IMO would have guess that belt slip would also make a noise and there would be evidence of wear on the belt and slipping pulley itself.
 
The Procharger has been on there for about 3 years. I put colder NGK plugs in it. I think I set the gap at .31. It has the original belt that Procharger sent with the kit. Still using the Procharger BOV as well. Probably have just under 20k on the whole setup.

I have a boost gauge on the car but the problem occurs so intermittently and quickly that I'm never looking at the gauge when it happens.

What else can you tell me about BOVs? A Google search revealed some rather negative feedback about Procharger's supplied unit. Whats a good replacement piece? Where can I get one?
The Vortech supercharger I installed on my 03 GT years ago came with a Bosch BOV. That thing was crap. I simply went on Ebay and found a BOV that was about like $40. The Bosch was a plastic or rubber type material...the one I got off Ebay was more of a metal or aluminum type material. And it held up very well in comparison to the Bosch. Also, I swapped out the Vortech supplied belt for a Gator belt. That helped a lot also. But first you may wanna get someone to watch your boost gauge while you're driving to see if you're loosing boost when these incidents occur. That right there will tell you a lot about whats going on. But from what you're describing I'd have to say it is either the belt or the BOV. Since both have 20,000 miles of use I'd say change the belt first and see what happens.
 
I will get the charging system checked out. The Battery is a few years old and I check it regularly, cleaning any corrosion build up. It doesn't corrode much but I stay on top of it. I try to keep the terminals covered in the protective goo stuff with felt protectors. The terminals are good and tight.

The alternator on the other hand is original to the car. 10 years old with about 113xxx miles. Has the original starter on it too. Probably both due for replacement but they keep her trucking.

I can say that when this hiccup occurs it does not affect the dash lighting or diagnostic lights on the gauge cluster. Have you heard of anyone having a similar experience?

The belt is in pretty good shape. I had the belt off a few months ago. No signs of breakage or dryness in the ribs. The sides of the belt seem intact as well.

351-Did the valve you bought bolt right in or did it take some modding to make it work? If so, what did you have to do?
 
It fit right in on the pressurized discharge pipe that runs to the TB. One hose going into the BOV and one hose going out with a vacuum line on the top. Simply loosen the clamps holding the BOV on, slip the hoses out of the BOV, slip the hoses onto the new BOV, then tighten the clamps, and then make sure the vacuum line goes right into the top. Not even a 5 min job.
 
What about the battery terminals especially the battery negative?

Are the grounds around the radiator core support clean and tight?

Has the alternator been tested for excessive AC ripple?

My recommendation was given in post #4 with regards how to rule in/out an electrical problem. If the problem is infrequent it may take a long term approach to monitoring. Hence the reason for the "add a fuse" so that it's possible to monitor for an extended period of time.
 
The battery terminals are in good shape. Next time I'm out, I will inspect the grounds. Come to think of it, the ground from the block (on the driver's side) is kinda rusty. The ground strap I stuck in between the stud and the retaining nut because they rusted and fused together. Could that be an issue?

I'll look into the add a fuse as well.
 
:zombie: The thread has risen again. Just an update.

The car is running like crap. I flogged it the other night and now there is consequences. The header is leaking a little bit on the passenger side. Not too big a problem. I'll just have to change that gasket out.:nonono:

Bigger problem is the hiccup has turned into all out falling on its face. Once it hits 5 pounds of boost, its like somebody puts a limiter on it. It stops all acceleration and won't rev any higher than whatever rpm its is at when it hits 5 psi. The thing starts sputtering and takes a dump. I spoke with my tuner and he said it sounds like either the fuel pump is about to crap its pants or the MAF is pegging. Its sluggish over all but fairly compliant when driven normally.

Diagnosing these is well over my head, so its going to the tuner tomorrow. He'll figure it out. I am incredibly disappointed but I suppose I've done well to keep the car going this long without taking to the pros.
 
Got the copper core NGK TR6s and I gapped them at .030. Probably about 19xxx miles on them.

Hoping to hear back from the tuner tomorrow. Fingers crossed its nothing too horribly damaged or expensive.

I really hate waiting. I am grateful they got me in on a holiday week, though.
 
Well that is the same plug I use and close to the same gap I set. However that is a copper plug and 20k miles is a lot of miles on a copper plug. You might inspect them...
 
Every year. My Cobra only gets about a few thousand miles per year. So I just change the oil and plugs every spring. I am at about 71,000 miles on it. State Farm gives me a discount for keeping it under 5k miles per year.
 
Has anyone here maybe thought of a fuel delivery? How old is the fuel pump? I remember mine did some What the same thing when mashing the pedal due to a starving problem. Just food for thought