C4 serging, bucking and acting strange
Thread Starter
Racer
Joined: Jun 2004
Posts: 391
Likes: 0
From: Lisle IL
CI 6-7-8-9-10 Veteran
C4 serging, bucking and acting strange
My 1988 has developed a weird problem recently.
At first, I had to let it warm up to about 170 Degrees collant temp before I could drive it. If I did not let it warm up then it would serge & buck & really run like crap. I would have to shut it off, let it sit for like 1 minute, restart & it would be fine.
Recently, this has happened even if I let it warm up, and very recently it has happened after it has beed drivin for a while. I had it on the highway, slowed down & stopped to pay a toll & when I pulled out of the booth it started doing it again. I shut it off & restarted and it was fine.
I have changed the O2 sensor & the coolant temp sensor and reset the TPS to .54.
I talked to the guy who burned my chip and he asked me to check the fuel pressure and the block learns. Called him with the results and he said everything looks like it opperating correctly with the chip.
Other than this the car seems to drive & run fine.
BTW it has a 383 with a paxton supercharger.
Has anyone run in to this type of thing? Please help.
At first, I had to let it warm up to about 170 Degrees collant temp before I could drive it. If I did not let it warm up then it would serge & buck & really run like crap. I would have to shut it off, let it sit for like 1 minute, restart & it would be fine.
Recently, this has happened even if I let it warm up, and very recently it has happened after it has beed drivin for a while. I had it on the highway, slowed down & stopped to pay a toll & when I pulled out of the booth it started doing it again. I shut it off & restarted and it was fine.
I have changed the O2 sensor & the coolant temp sensor and reset the TPS to .54.
I talked to the guy who burned my chip and he asked me to check the fuel pressure and the block learns. Called him with the results and he said everything looks like it opperating correctly with the chip.
Other than this the car seems to drive & run fine.
BTW it has a 383 with a paxton supercharger.
Has anyone run in to this type of thing? Please help.
Race Director
Joined: Feb 2004
Posts: 12,518
Likes: 19
Re: C4 serging, bucking and acting strange (Blown383C4)
I would check mass air sensor and wiring connector. Had a similar problem and it did not throw a check engine light. If you can borrow a sensor from a friend I would swap it out to see.
Thread Starter
Racer
Joined: Jun 2004
Posts: 391
Likes: 0
From: Lisle IL
CI 6-7-8-9-10 Veteran
Re: C4 serging, bucking and acting strange (Pete K)
Pete K - How did your problem begin? I bought the car with the mods already done. Would the mass air sensor needed to be changed after the 383 & supercharger, or does the chip take care of it? I ask because I don't think I can borrow one, I'll just have to buy one and see. Just need to know what to get. Thanks.
Race Director
Joined: Feb 2004
Posts: 12,518
Likes: 19
Re: C4 serging, bucking and acting strange (Blown383C4)
My problem began 1/2 way down the 1/4 mile. Scared the heck out of me.On my procharger install I had to cut the harness at the maf sensor. I had to solder wires on to lenghten them. I assume paxton is similar. Check this area. Most people use crimp butt connectors and they corrode inside and fail. This is something you can easily check without spending money. If butt connectors are there cut them out,solder and heat shrink them back together.
Race Director
Joined: Feb 2004
Posts: 12,518
Likes: 19
Re: C4 serging, bucking and acting strange (Blown383C4)
From the factory the maf sensor was 3 inches off the end of the throttle body. The supercharger kits normally relocate the sensor. This is th treason for extending the wires.
Race Director
Joined: Feb 2004
Posts: 12,518
Likes: 19
Re: C4 serging, bucking and acting strange (Blown383C4)
Unlike the mustangs we are stuck with the factory sensor. It cannot be altered. If something new is on the market that I am unaware of, hopefully someone will chime in with info.
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Re: C4 serging, bucking and acting strange (Pete K)
My `97 was surging & stalling. I was going nuts trying to find the problem. then while changing the plugs, I dropped the ratchet down in the driver`s side headlight well, & while getting it out, i found a rotted & broken vacuum hose. replaced it, & so far no more surging.
Ken
[Modified by kenv, 9:53 PM 7/7/2004]
Ken
[Modified by kenv, 9:53 PM 7/7/2004]
Melting Slicks
Joined: Dec 2000
Posts: 2,719
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From: Fremont Oh
Re: C4 serging, bucking and acting strange (kenv)
perhaps a couple things...
If you unplug your MAF sensor it will set a code but if the engine runs smooth that will tel you right away, as the engine will use a MAP as a backup. I had this happen on both my 87 and 89 ,. the some what intermittant could be that the burn off relay is not working properly.
Another issue on the LT's anyway.. they was an issue where if you exceeded the frequency of the MAF sensor it would cause weird things to happen. sisnce you are running a 383 whith "X" anount of boost that could be an issue as well.
I'm not real sure about the 1988's but Grannetelli makes a MAF that you can calibrate (at least for the LT1's) it has two adjustments to calibrate it to your cam ..etc. etc.
If you have like tunercat or a logging program ... monitor the MAF and see what it looks like if you can repeat the problem...
Gernealy I'm at about 49 -50 lb / min on the MAF at close to 6000 RPM's
hope this helps...
MO
If you unplug your MAF sensor it will set a code but if the engine runs smooth that will tel you right away, as the engine will use a MAP as a backup. I had this happen on both my 87 and 89 ,. the some what intermittant could be that the burn off relay is not working properly.
Another issue on the LT's anyway.. they was an issue where if you exceeded the frequency of the MAF sensor it would cause weird things to happen. sisnce you are running a 383 whith "X" anount of boost that could be an issue as well.
I'm not real sure about the 1988's but Grannetelli makes a MAF that you can calibrate (at least for the LT1's) it has two adjustments to calibrate it to your cam ..etc. etc.
If you have like tunercat or a logging program ... monitor the MAF and see what it looks like if you can repeat the problem...
Gernealy I'm at about 49 -50 lb / min on the MAF at close to 6000 RPM's
hope this helps...
MO
Thread Starter
Racer
Joined: Jun 2004
Posts: 391
Likes: 0
From: Lisle IL
CI 6-7-8-9-10 Veteran
What spark plug should I be using? Currently using AC Delco #41-629 with a gap of 35. The guy I got my chip from recommends an Autolite non platinium plug. He says that the resistors in these plugs are more reliable and not as affected by heat.
Thread Starter
Racer
Joined: Jun 2004
Posts: 391
Likes: 0
From: Lisle IL
CI 6-7-8-9-10 Veteran
Originally Posted by Mo_Bandy
the some what intermittant could be that the burn off relay is not working properly.
MO
MO
Thread Starter
Racer
Joined: Jun 2004
Posts: 391
Likes: 0
From: Lisle IL
CI 6-7-8-9-10 Veteran
The vacuum is reading 9 - 10 iches at idle. It will go down depending on throttle position. Does this seem right keeping in mind that I have a blower? The idle seems fine @ about 800-1000 rpm.
Racer
Joined: Apr 2003
Posts: 371
Likes: 0
From: Kingsport TN
Had a similar problem with my 89. Make sure both the maf and ecm are ok. First sign of a ecm going bad is irratic reading from your instant mpg and trip odometer. I didn't believe it when I was told, found out after throwing lots of parts at it, along with a few wrench's. 
Good luck
:flag
Good luck:flag
