What make my tpi suck loud at idle and also when you are driving.It seems to go and come but today I put plugs in and it ran quiet like it suppose to but next time I cranked it up the sucking came back tried changing MAP and TPS to no help.The engine is new 383 with 50 miles on it.Changed IAC and cannot seem to get it right.Just started last week on the way to trans shop to get700r4 adjusted.You could hear it pulling up to the shop. Thanks for help

What do you mean sucking ? Running bad or a sucking air sound ?

Please elaborate.

sucking air like going real lean and I mean loud sucking but it ran fine one time yesterday and then next time I ran it it was back to sucking,think it my be 02 changed map from my other car and didn't help.When it really sucks it run a little rough but when it doesn't smooth.No codes on computer.Thanks for help

I am having the same problem and cannot figure it out. I have replaced the IAC and completed the reset procedure with no luck. It is at the shop now, so I will let you know if they find anything.

A vacuum leak will cause a sucking sound. The unmetered air will cause the engine to run lean, therefore rough. The TPI intake has multiple mating surfaces to lead to an vacuum leak. Some people even forget to reattach their brake booster, and wonder why it runs rough!

Go back over the intake area and find your leak(s).

Brake pedal would be hard as a rock if vac hose was off and difficult to drive... but certainly a large source.

Only time I get a loud air sound is when air intake hose is off the throttle body. Was the TPI coolant hoses eliminated or the hose that goes to the valve cover ? PCV connection to plenum?

Check all vac hoses - tpi/runner/TB gaskets - is MAF connected to filter box? Vac hose under plenum at front by throttle linkage - EGR valve, heater valve vac hose

can't pinpoint the sound while running ?

Just throwing the kitchen sink out there..

Let us know what you find.

Thought it might be the booster but disconnected and still the same.It ran fine 1 time the other day but when I shut it down to check voltage at TPS the next time cranked it suck again.No fault codes going to change 02 today maybe if I have time.It does sound like vacumn leak.Will spray ether around to see if I have a leak.Or some propane.Something like this will drive you crazy.Have closed off all lines that hold vacumn.Thanks for help

Flatmotor40, can you explain to me the propane trick when checking for vacuum leaks. I never heard of doing that before. Thanks.

If you have a vacuum leak, the engine is getting too much air and going lean. By waving an UNLIT propane torch around the suspected vacuum leaks on the RUNNING engine, the engine will suck air + propane into the engine. This added air + FUEL will cause the engine to increase RPM.... and confirm you have a vacuum leak, and generally where it is.

Thanks MoJoe for the answer. I was thinking that's what is was about, but was'nt sure.

After changing throttle body yesterday it ran smooth no sucking.Shut off ready to go for ride and next time crank sucking came back.Repeated crank sometime suck sometime not.Put pressure gauge on fuel rail late yesterday will try today after eating turkey.Hate it when it doesn't do it all the time.No codes on computer.I know it seems to lean it out big time.If any more help please let me know.The prpoane method does work to find a vacumn leak but when sucking start idle is high and ldle is rough.Thanks for help

Can spray carb cleaner just the same - but eng must be cold, dangerous otherwise.

Propane trick sounds neat too - have to try it.

I think it i something to do with IACV. Sounds lie Darth Vader constantly sucking air in is how I described it when I was experiencing the same thing. It seems I just made all the adjustments and it was largely eliminated.

This has to be a vac leak somewhere. That's why it's going lean. When I put my TPI back together I drove it just a few miles and it started trying to idle high and made a whistle sound. Almost every one of my runner bolts had loosened, I tightened them again and haven't had anymore problems.

I"ll check bolt and tighten up bolts today but seems like it would do it all the time not once in a while.Put pressure gauge on it haven't been out to shop in 2 days but maybe today will mess with it.Sometimes just get away from it.But will try to get it fixed.Thanks for help.Wildjyoung have you heard about yours yet

Flatmotor40, I have that sucking noise too, coming from the air filter. On my car, it occurs when the engine is cold. It also runs a little rough when cold. After the motor warns up (3 - 5 minutes of idling), I can hear the noise wind down similar to a turbine winding down. Afterwards, the idle smooths out. Have not been able to figure it out for at least 2 years. Really weird. I'm going to try the propane trick to look for a vacuum leak. I agree with MrPackstin that it has something to do with the IAC valve.

I've changed the IAC and can't seem to find what is wrong.This is a tpi that I installed in my 71 Monte Carlo.But I have one in my 55 Chevy with no problems.This one is driving me crazy.Could bad IAc but will continue to try to find out.Thanks for help so far.It idles up way high when the sucking starts.but I'm having to crack throttle open a little to get it to crank and run.Maybe take it out today for a short ride.Will a knock sensor do the same thing.

Knock sensor has no bearing on idle speed. I'm sticking with vac leak.

I just had my plenum and runners off for a fuel inj replacement. I bought a new tpi gasket kit, comes with a TB(throttle body) gasket also. Once I went to replace the TB gasket I noticed my bolts were finger loose - all 4 of them. I must have been sucking air and loosing vacuum enough to cause the egr to not work...


Check your TB bolts, and are the runner/plenum bolts torqued to 25 lbs?

Edit - just notice you said you change the TB .... got to be a cracked hose some where ??
How abot PCV valve hose, also the barbed fitting into the intake comes loose sometimes, my Camaro had a cracked hose, it worked unless I lifted it up, then split opened up.

Let us know what you find.

Chad, if the ECM retards timing when it receives a knock signal, won't that reduce idle speed?

Thanks still running down problems.Out of propane in little bottle need to get a new one this week.

A car im working on just did this same thing. Drove me nuts for 2 weeks. Found the new IAC to be frozen internally. Swapped another one I had, did the relearn procedure again and now its back to idling quietly again.

I'll dig out an old one and try it but I now wonder if I have an intake gasket leak.Guess I'm jumping around trying to find the problem. Thanks again

I guess it could yes. Unplugging it should tell you right quick if that's the problem.

Vacuum leak behind dash?

From the heater control vacuum lines

Tried the propane today and nothing.removed all vacumn lines still the same will change computers today with one off my 55.Kinda thinking it could be a timing problem now that we have changed and checked other stuff.Also went back to an older IAC and still the same Thanks for info trying to solve this.

After propane couldn't find a leak went to timing and for some unknown reason the timing had retarded and advance till sucking went away and went for a drive boy did it run smooth and start up on 1 turn of starter,So always recheck timing.Thanks for help