Hey Tampa Racing.

I just got my hands on a 91 Supra with the Stock 7m-GTE. About 300k miles, but it's all one hundred percent stock. Really good find, if you ask me (aside from the mileage). Anyway... There's a huge boost leak. I can tell because of some obvious symptoms, and the classic big ass puff of black smoke coming out of the exhaust after boost. The previous owner said that the Turbo has a lot of shaft play, and that's the ONLY problem with the car. Let me know if these symptoms sound normal: I can't push the car past 4k RPMS in gear (it starts to sputter and slow down), and whenever I go past 2.5k RPMS and then throw it in neutral, it'll have trouble catching up to a normal idle. In some cases, it won't be able to catch up at all, and it'll just stall out on me, unless I gas it up in neutral to help stabilize it. At first, I thought it was the MAF sensor going bad, so I swapped it out with the MAF from my project Supra. Unfortunately, it didn't help at all, which means either both MAFS are bad, or it's not the problem. The Turbo itself is definitely a factor and will have to be swapped out regardless, but I'm trying to figure out whether that's the only problem or not. I'm also thinking the Intercooler piping may be leaking additional boost, since it's all stock piping, and it's been about twenty years, and a shitload of miles. Could the TPS have gone bad? The A/F ratio is definitely off, and I feel like it's not responding like it should be to the throttle. Any input would be appreciated. Thanks a bunch.

 

i had i 7mgte and it had three cracks around the internal wastegate of the turbo when i bought it and it didnt have anywhere near that amount of miles. so that might be a prob u have. just my two cents. lol

 

Hmmm.. So, that still relates to the Turbo. I plan on replacing the Turbo, I just have to acquire/rebuild one.

 

It depends on how much you love the car in stock trim (i.e. original motor) and what you want to do with it. You could end up spending a LOT getting that 7mgte running perfectly and even then, you run the risk getting a blown head gasket or spun bearing (which they are NOTORIOUS for). It has a lot of mile and you probably need to start with a fresh rebuild. One thing on your side is that there are a lot of 7M parts around that are cheap. Why not contact Justin at Hybrid Motorsports? He can most likely help, and if you're looking at doing a swap, he can also help with that as well. I don't have the shop number, but they have a shop forum on here.

 

thats got to be a record for a 7m with that many miles hahaha

 

Pull the codes.

 

no

Anyways...to the op, if your boost gauge is working, drive the car, hit boost, and stay in boost....if you hear the waste gate open, then this "crack" is probably not going to be ur problem, I had my stock turbo running 14psi, with a crack on the wastegate and it showed 370HP with larger injectors and the lexus MAF. But agian its probably not ur problem, ur "leak" is probably coming from your 20 year old intercooler piping and its equally aged couplers. Have your car on and get some soapy water, and make a lot of suds. Then poor it on the couplers, and see if theres any bubbles, or just visually check for cracks in the piping. I had the same problem, being a boost leak, and it turned out to be 3 cracks through-out my piping. Anyways let us know what happens, and maybe some pics?

 

You could always make a boost leak tester for ~$10 from the Home Depot.

 

Don't listen to this guy, he doesn't know anything about Supra.....jk jk, My CPS would probably still not be working right if it wasn't for him.

 

Alright, I probably should have updated a while ago, but I barely have enough time to check on TR these days.



Anyway, the problem was the Turbo itself. It was blown to bits. So much so that the propeller and compressor fans were scratching up against the housings at an incredibly aggressive angle. That's why there was so much resistance past 3.5k RPMS.



It would also spit out oil all throughout the intercooler piping and the Intake manifold, due to the blown seals. The turbo was literally kicking it's own ass. Well, I have a few CT26s lying around, but they're all blown, and I've never rebuilt a turbo before. And although I'd love to give it a try and rebuild one someday, I wouldn't trust my amateur build on my Supra. I had no choice but to buy a new one. And I figure since I'm going to buy a Turbo, I might as well upgrade. I didn't want crazy power since, this was going into a DD Supra with way too many miles to even consider performance. So, I bought a freshly built 60-1 CT-26. During the removal and install, I stripped every bolt, and nut you could imagine, and it ended up taking me two days just to remove the turbo. Puddles of PB Blaster sitting on the nuts overnight helped me out. Anyway, once the turbo was out, and the coolant was drained as well as the lower coolant hose removed, I took the time to inspect as many vacuum lines as I could see. I found about five completely severed lines, and I replaced them. Hoping for the best, I installed the fresh turbo, and started putting everything back together.





Once the turbo was finally in, I filled the radiator with coolant, and I tried to burp the system, but it wasn't really working, and the Supra almost overheated a few times.



Eventually, I got it all settled. and I took the Supra out for a spin, at 3am (when I finally finished). I finally felt my Supra boost for the first time ever. It felt awesome. Conclusion? The car was unable to rev past 3.5k rpms because the turbo was blown, and there was just too much resistance from the turbo that it was overworking the motor. The car would stall out constantly because of all the damaged vacuum lines.