High RPMs, Radiator Hose Blowout!

[OneBadTT]

What does your PowerLogger show in the 'Prog Idle' box? It's the one under the IAC Counts box. - I'll double check but I think it was somewhere around 900

As far as a vacuum leak,I replaced my 23yr old hoses after finding some that were attached,but were more partially stuck on,than properly attached. Many looked good on the outside,but were hard and crumbly. - I have been replacing the vacuum hoses with the same hose but haven't finished.

Got new ones from nos4gn.com. Under $4 for 72 inches of each size. Shipping was faster than a speeding bullet.

Have you done the carb cleaner spray test for vac leaks? - I haven't tried this yet. How do you do this?

Do you hear a hissing sound at idle?- I can't hear a hissing sound but the engine is loud and it is hard to pick up a hissing sound.

The 1,600rpm idle is indicated on the PL and not by the inaccurate factory tach. ?- It shows on both the Powerlogger and the Scanmaster.

I put another chip in that I had in before the TT chip and the idle went down to 1300 RPMs. I don't know if that is low enough for the emissions test though.

 

[HighMileage]

What happens to the idle if you unplug the PCV and cover the hose with your thumb? Unplug it at the hard line. Much easier than getting down in that valley.

The carb cleaner test is a test where you spray the carb cleaner in suspected leak areas with the engine running. Avoid exh and coils. If there is a vac leak in the sprayed area,idle will change.

I've done this test many times over the years on many a car. Never had a fire. Quick bursts is all that is needed.

<Many disclaimers attatched due to slip/fall lawyer purposes>

One other suggestion would be to re-post this thread with the High Idle in the subject line so as to possibly reel in someone who has had the same issue.

 

[Chuck Leeper]

"and bought a vacuum pump tool. I'll have to read up on how to properly check vacuum, but I played around a little and I tried to pump the vac hose that comes off of a "y" to one of the hard lines that goes to the block- no pressure measured at all. I don't know if that is normal or not."

You don't use a vac pump tool to check vac. You use a vac gauge, hook it in to a line, start the engine and read the gauge..

A different chip... Is it burned for the injs that are in the engine??

 

[Razor]

Razor- I tried what you said and it had no impact. The IACs did go up but as the car sat in park, running, the IACs decreased to zero and stayed there. I think I am going to change my chip out to the stock one and see if that helps. If not, then I am going to start searching for the vacuum leak.

Charlief1- I wish it was an 86 right now, but it's an 87. :frown:

When you first start the car the IAC is suppossed to be high in number. And as a small amount of time passes, the number reduces it self to get the engine to a target idle. Lets say 700 RPM's. If the idle is higher than the 700.. then the IAC keeps going down to zero. Once it hits zero.. it cant go further.

So if your TB is shut.. IAC is at zero.. there is no way through a normally operating throttlebody that you can have a high idle. Unless the air is coming in after the blade. Causes of this can be blown out EGR gasket, blownout distribution gasket on top of the TB, cracked distribution block, missing/blown TB gasket/plenum gasket.

If you want to eliminate all the vacuum lines as sources.. take the 2 screws of the distribution block, lift it.. place a rubber glove/gasket/etc to seal it completely and put the two screws back on. This will block off all the hoses.. see if your idle comes down, if so.. you know where to start looking.

I doubt it will pass anything with a high idle.. especially if it has a vacuum leak.

An old timers trick to find vacuum leaks is to get a long pipe like 1/2-3/4 diameter.. 3 foot long.. pvc is ok.. put it to your ear and move it around the engine bay listening for a "HISS". You'll find it easily.

 

[Warp6]

Have you checked your oil during any of this? Make sure there's no coolant in there.

 

[OneBadTT]

Thanks Razor, thats a great explanation. I'll try this tonight and see if I can eliminate the hoses.

Warp6- I did check the oil and I didn't see any evidence of contamination by any other fluids

Thanks ChuckLeeper, I'll try the gauge.

Thanks High Mileage, I'll try the PVC check too

Thanks to everyone for your thoughts and ideas. I feel like I'm getting close to solving my problem.

 

[TURBOPOWERED68]

Send me a PM. I'm just south of you in Hillsboro. I'll be more than happy to help you if you need it.:smile: You need to do a compression test and a leak down test at the very least. You can get the tools at AZ on the loan a tool program. If you want I will give you my number and will walk you through it.:biggrin:

Charlie you are one heck of a COOL DUDE.

 

[GNRick]

Smoke machine

Best way I've found to check for vacuum leaks is with a smoke machine. This is what my mechanic uses. They cost over $1100 new. You inject smoke at low pressure into a vacuum hose and where it comes out is your leak. Now, through the miracle of the internet, I checked Craigslist for you and found two in your area. Here they are:

Automotive Diagnostic Equipment

Evap Diagnostic Smoke Machine

 

[OneBadTT]

I tried a few things this evening:

1. Used a vacuum gauge to check vacuum- measured 16- is that a good number?

2. Sprayed Carb Cleaner around the engine while it was running- around the plenum, around the distribution block, around all bolts, around the up pipe. around the IAC valve, around the valve cover edges, around the EGR, around all hoses.- no change in RPMs- staying at about 1500 tonight.

Should I spray anywhere else?

3. Forgot to mention yesterday that I did change my chip- back to a street performance chip good for my set up (not as good as the TT chip though ).

4. Put a rubber glove between the distribution block and the plenum- started engine and let run a little- no change in idle.

5. On start I noticed a very small wisp of smoke coming up from around the turbo- nothing significant but I wonder what that is. It happened three different times at start up while testing.

6. I tried to get new EGR gasket, TB, and Plenum gaskets at a local AC/Delco supply store but none of these available locally. I'll need to look some more tomorrow. My distribution gasket and distribution block are only 3-4 months old.

7. I tried a pipe to listen for hissing. It sounds like there could be hissing around the front of the plenum by hoses but my hearing isn't good and the pipe was actually a lower radiator hose. :redface:

8. I'll try the PCV trick when the car cools off.

Sorry if I mispelled- that carb cleaner kinda got to my head...

 

[HighMileage]

When you did #4 and there was no difference,my #8 idea goes down the toilet...

Not sure where to go from here. IAC is normal. No vac leaks.

If you have a spare ECM,try that. ?? Worth a try if you have one. Put it in,go for a drive and see if it settles down. ??

Maybe send a PL file so the experts can look at it.

 

[GNRick]

I recently replaced my throttle body shaft seals as one was leaking. Caused high blm's. Found it from the smoke method.

GBodyParts.com Online

 

[OneBadTT]

Thanks GN Rick- I'll order some seals and replace them. That smoking machine is very tempting at that price but it is still over my budget. I could really use that one!

 

[GNRick]

I made a leak detector similar to this one:

How to: make a slightly more baller boost leak detector - evolutionm.net

I used a toilet bowl plunger that I bought from Lowes for $2 and attached the blue rubber piece to the inlet of the turbo. With the other parts as seen in the picture, I connected it to an air compressor. Just use low pressure air, like 5- 10 psi, and you should hear any air leaks.

 

[OneBadTT]

Thanks GN Rick- that's a cool tool.

For anyone that would like to take a stab at looking at my powerlogger files to see anything that might help figure out what other problems I might have- here they are:

The #5 is the last run with the TT chip in and the boost turned up to 15#s or so. Alky- non-progressive- comes on around 7# boost pressure.

The #6 is with an older Street Performance chip set up for my combination.

#3 is a couple of runs before #5.

 

[mikestertwo]

The files don't show much. Don't use the older chip...file 6...your running rich...the BLM's are maxed out at 105. The concensus is you have a vacuum leak somewhere. Keep looking.

 

[OneBadTT]

It's a New Years Eve miracle! Here's what I did:

1. Removed the Throttle Body and cleaned it thoroughly. I noticed some build-up around where the blade touches the throttle body when it's closed. I scrubbed to fully clean.

2. Installed my new IAC angle boss and a new IAC valve.

3. Removed the Plenum and cleaned thoroughly. There was a very heavy build up in the square opening in the front of the lower manifold (name??) that the plenum is attached to. It was thick and gunky. I removed it with a screwdriver by lightly scraping down into the square opening until I hit bottom. I tried to remove as much of this stuff as I could.

4. Once all was cleaned I reassembled with new throttle body gasket, and a new distribution block gasket. Also used a new gasket for the IAC valve.

5. Disconnected the battery and put my newer TT chip back in.

6. Reconnected the battery and screwed the IAC adjustment screw all the way in.

7. Started the car and the TPS was .80. The IAC steadied at 184.

8. Began working back and forth with TPS and IAC. Restarted the car after each adjustment.

9. For the first time in years my AF was at 6, down from 12, at idle. My IAC is steady at 10 during idle. My TPS is at .40. My RPMs are exactly at 800!

I am going to take it out again this evening with the powerlogger and see what kind of readings I get!

Thanks to everyone for your help. I am hoping this has resolved my vacuum leak problem. I wish I knew exactly which thing I did fixed the problem, but at least the combination worked. I hope this helps others who are going crazy trying to chase a vacuum leak, high RPM, low IAC problem.

I'll update everyone again after making a few runs. Tomorrow I am going to try and get a passing inspection (if they are open)!

 

[OneBadTT]

Here is my first run after fixing the vacuum leak. I see 2 problems right away:

1. Knock Retard (first time in years I have seen any at all) 10.6 for a split second!!!

2. Full throttle TPS is low.

Does anyone see any other alarming things that I missed? Any suggestions for improvement? Thanks.

 

[Razor]

See when you set TPS.. what is done is loosen both screws and pull the sensor forward torwards the radiator. While pulling it forward keep tension on it to setup your .38-.46 setting. This will yield the highest number from the sensor. If you let the seneor glide back torwards the firewall.. it will give you the lowest WOT numbers. Some would grind the slots a little to move the sensor forward.

As to your knock.. if its real.. check your alcohol system. if its false.. thats something else.