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corvette strangulation

4066 Views 28 Replies 7 Participants Last post by  99c5ls1
does anyone know where i can get a catalytic converter test pipe so i can test the car and see if the converter is blocked?? koff koff :smack :surprised :crazy:
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I don't think there is such a critter. But if there is i'm sure other people would like to buy one:thumbsup:
Take the car to a muffler shop (the smaller the better) and tell them you race the car and need one to swap in for race day. If you find the right swap they will make one up for you.
If you have visual inspection simply gut the thing with a very long half inch drill bit and a hammer and long chizzel. Make sure you get the fiber inner heat shield out by soaking it too.
I have seen the test pipes for sale on ebay, but the muffler shop is your best bet.
yet another in a long line of reasons to own a decent welder.......

I can,t even imagine being in this hobby/obsession without at least a oxy-acetolene torch or a stick welder of some type.

heres a small sample, just remember these names


heres an old post that cover much of the info, LOOK THRU THE LINKS

a decent arc or stick welder will do a good deal of whats likely to need welding, an oxyacetolene torch is versital, a mig is really easy to master and a good tig will handle about anything you can name plus aluminum

TIG (Tungsten Inert Gas Welding)

basically youve got a controlable electric arc in a gas shield that you use similar to a oxy-acetolene flame to melt the material and feed a rod of similar material to flow and join the peices
This process is the toughest to learn. The electrode is composed of Tungsten, and a current is flowed through it controlled by either a foot pedal, a hand switch, or a fixed current on the machine itself. I am learning TIG using a foot pedal, the more you press down on the metal, the more amps you get. Once you get enough current flowing to get an appropriate sized weld pool, you start dabbing a filler metal into the puddle as you move the electrode further down the work piece. TIG allows you a great amount of control because you regulate how much current the electrode gets and how much filler metal the weld pool gets. This process is very slow compared to the other types though. in my opinion its by far the best process simply because you can CONTROL BOTH THE HEAT POLARITY AND MATERIAL FEED CONSTANTLY MAKING ADJUSTMENTS IN BOTH SHOULD YOU CHOOSE

MIG - (Metal Inert Gas)

MIG is the easiest process of welding. A feeding gun is used to feed a spool of filler metal wire into the weld pool. in effect you feed a charged wire into the weld are where it melts on contact due to the current arc ,Current is usually switched on and off by means of a trigger on the gun. Amps are usually controlled by a dial on the MIG machine itself, meaning that you cannot adjust current in the middle of welding. Though, with some machine you are able to get a foot pedal to control Amps while welding.the better machines allow you to vary the speed of the wire feed but you set the electrical energy (heat with a dial), its extremely fast and simple to use but your basicall shooting molten wire into the area to be welded.

Arc Welding (stick)

Arc welding is mostly used in industrial applications. An electrode is used to strike an arc, the electrode then melts away to deposit metal into the weld pool. The electrode is coated with a variety of different materials which are used to help keep the weld pool from being contaminated.

TIG and non-flux-cored MIG both use a variety of different shielding gases to help keep the weld pool from being contaminated depending on what metal is being welding.
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ok got the welding lesson. BTW did i tell you im a CWI?? Certified Weld Inspector? missed that sorry. anyway, pulled the cat off and the car does the same as before just doesnt want to run. so, the MAF is new MAF solonoids (both) are new fuel pump solonoid is newcar still wont run with the codes clear. once the check engine light is on it will run till warm idle surges and it will die. strong smell from the exhaust burns your eyes. any ideas here? this book of matches is looking really good at this point
have you reset the memory then pulled trouble codes?

most problems like that are caused or at least effected by a faulty sensor, but Ive seen a bad fpr (fuel pressure regulator) cause similar problems, whats the fuel rail pressure and how long does it take to drop after the engines turned off
(should be about 37-42 PSI and take several minutes to start dropping off slowly)

things like that are harder to isolate unless your on site
thats where it gets weird. clear the codes, it doesnt want to start. once the check engine light comes on it will run till warm, then it doesnt want to run. scanner says MAF voltage is high, TPS voltage is low. havent visited the fuel pressure yet.
I seem to remember that if the TPS is not positioned correctly these will run horrible - - I know you need an ohm meter to check it and a service manual to give you the settings.

Can't tell you anything else - - I frankly don't know.
set the TPS to .54 exactly what the book calls for. thats one of the things i dont understand. got to figure this out. its driving me nuts :nuts: :nuts:
because the darn CPU takes input from the sensors and its not like a carb that self adjusts to a large extent to match air flow rates, things like a badly adjusted TPS,IAC,or a bad oxygen sensor, or engine heat sensor or fuel pressure reg. can cause all kinds of weird problems, what I generally do if the source is not obvious is adjust the IAC,TPS, and fuel pressure then check for loose connectors, injectors that are not clicking and heat sensors or OXYGEN sensors that are bad or fouled.

youll need a few tools if your going to be doing this correctly on a steady basis
have the scanner, and the multimeter. is a fuel pressure gage that only goes to 10 PSI enough?
"is a fuel pressure gage that only goes to 10 PSI enough?"

NO....the corvettes fuel pressure should be in the 37psi-42psi range at idle
the harbor freight gage you refered to only goes to 10 PSI of out put pressure. thats why i asked.
your correct I SHOULD have been more detailed in my responce, I really wish you were located MUCH closer as this stuff is generally far easier to deal with when HANDS ON rather than thru my lousy typeing

I meant it to be used as a vacuum gauge for testing/ & trouble isolation,, and didn,t get into enought detail. this should help

you can get cheap near throw away fuel pump testers off EBAY, below is a generic example, but theres several sources

for under $25
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took the day off from messing with the car. a local corvette club had a cruise in at backyard burger so i was being nosey. there doesnt seem to be anyone here local that has a clue. they all seem to say im headed in the right direction but that doesnt help. some one somewhere HAS to have gone thru this before. i guess i will change the fuel filter (did i mention it was low on fuel at the time) may have sucked something up. and while im down there do another new O2 sensor incase i burned that one up. possibly do the TPS also seeing that i have the code 22 coming up.
#22: Throttle Position Sensor Circuit Voltage Low.

not being on sites a b#$%^ but ID be checking both the connectors and engine grounds like the one on the rear of the drivers side cylinder head , check the wires and Id check the battery voltage under load too! then ID try swapping the TPS with a KNOWN good one, BTW SALVAGE YARDS usually seLL those DIRT CHEAP, and its not necessary to get them excluesively from a corvette, some camaros of approximately the same age have similar parts like that.BTW have you got any buddies with a 1985-1987 corvette you can talk into test/swapping your MAF with his just to do a 5 minute test??
IVE had MAFs that tested good (that were NOT good 100% of the time) do strange stuff at times
$31.00 for a TPS at autozone, gonna get that. the MAF is a new one,(re-man) does the same as the old one. wish u could look at this thing and see for yourself. i agree trying to discribe / diagnose this problem is tough this way.
If you suspect the MAF sensor or its circuits may be an issue, disconnect it and see how it runs, if it runs significantly better youve found your problem.(as Grumpy pointed out MAF's are notorious for being difficult to diagnose) If that doesnt change it, disconnect the MAP sensor and see how it runs, if it runs better youve found the area of your issue.

Youve got a scanner, check to see what youe ECT reads. If the engine coolant temp sensor is failed or youve got high resistance or open in the ECT circuit the PCM will think its -40 deg or so and will just dump fuel in order to try to get some of it vaporize and the engine to run.

Check to see if youve got wet(fuel fouled) plugs, you may have injector sticking open or the 9th injector not turning off.

As others have pointed out, a proper fuel pressure check is essential.
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