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View Full Version : Boost Problems!!



IkeyM
07-10-2015, 02:35 PM
Ok my 93 SC with the 1.7L AR has lost boost. It was boosting 19-20lbs now only getting 10-12lbs. I have checked all couplins, aftercooler,changed from 6rib sc belt to 8 rib. Seems to pull good at take off but flattens out after that. Any Ideas??

MadMikeyL
07-10-2015, 06:14 PM
I had a similar problem with my MP2, turned out to be one of the hose clamps on the bypass valve hose was stripped out, so it looked tight, but anything over 10psi would just get bled out past the loose clamp, and it didn't show up with either a smoke test or spraying carb cleaner around since at vacuum or light boost, it was still sealing.

davec73
07-10-2015, 08:21 PM
Have it smoke tested ikey. You will chase it forever if not but I bet your bypass valve is the problem. I had a coupler that was split in the middle but it sealed up good enough under boost. After getting rid of all those leaks I had to remove 22% fuel from my maf curve to get it close. Mine still needs some work but I finally bought my own smoke machine a while back that way when I do have it tuned I know for sure that it has no leaks.

aroot1
07-11-2015, 02:55 AM
Where did you find a smoke machine, and what did it cost you? I've been planning on building my own, based off u-tube baby oil and soldering iron designs. Would love something a little less redneck tho :p

Adam

davec73
07-11-2015, 02:37 PM
I was at a shop getting my car aligned and he bought a new snap on. I ran the snap on man down and bought his old one (couldn't have been used more than a dozen times) for 300 bucks. It has pressurized smoke and vacuum leak detection. I made one out of a party smoke machine but it didn't work out too well lol.

XR7 Dave
07-11-2015, 09:38 PM
Make sure your pulley hasn't spun on the hub. Did you torque it to 65ftlbs? Inspect for the belt rubbing on anything or signs of belt slip. Do your tensioners all have sufficient travel? Bypass could be stuck open, but I'm sure you checked that already.

IkeyM
07-12-2015, 05:32 PM
Make sure your pulley hasn't spun on the hub. Did you torque it to 65ftlbs? Inspect for the belt rubbing on anything or signs of belt slip. Do your tensioners all have sufficient travel? Bypass could be stuck open, but I'm sure you checked that already. David when i took off my old pulley there was what looked like a spacer came off on the inside of the snout and was stuck in the pulley? I assume this was a spacer so i just put it back in when i put on the 8 rib pulley. I checked the bypass,tensioners,belts.

KMT
07-12-2015, 06:07 PM
Spacer? Are you sure that wasn't the snout seal? Did you check the fluid level?

1FSTBRD
07-12-2015, 09:46 PM
I made one out of a party smoke machine but it didn't work out too well lol.

Too much partying is the reason why it didn't work out, maybe?

:D

XR7 Dave
07-13-2015, 04:55 PM
You have a QH, right? Check to see if MAFV and Load have fallen off or if they are still high. Should be close to 180% load with 18psi, 120% with 12psi.

IkeyM
07-13-2015, 07:31 PM
Yes i have a QH but its not in the car. I put my tune on a F3. Also im having problems with my laptop. I may have to get the new BE and get another GSALI file from you if i cant get it working.

IkeyM
07-15-2015, 09:07 PM
OK i removed the F3 chip and put in my QH and car wont hardly idle. took it for a ride and at WOT about 3500 rpm the engine was trying to cut off and on the way back couldnt give it no fuel or it would cut out. It idled good wth the F3 chip in somethin it never has done with the QH. David the load was at 153% at 3500 and the MAF was 3.2 volts. That should be about 15lbs of boost. My autometer gauge said maybe 12lbs. Still not where it should be with the 10% JS and 3.25" SC pulley. I think the QH has gone haywire or needs a new battery. when i tried to log after i returned my MAF was stuck at 0.11 and the AFR was 19 to 22 at idle. I reloaded the tune and no change. Still dont know what to do about the boost problem. I will send the QH to get it fixed. Car runs good with the F3 chip.

davec73
07-15-2015, 09:34 PM
There was a batch of qh chips that were bad. Something was wrong with them were they would drain the battery and not hold a tune