1998 TDI vs IDI diesels - General - VWDiesel.net The IDI, TDI, and mTDI source.

• 1998 TDI vs IDI diesels by homerj1 on 09 Oct, 2010 10:57
• Howdy folks,
  
  I've been driving a variety of 93-96 Jetta\golfs with AAZs  and appreciate the simplicity of the idis thanks to our friend Rudolph D.
   
   I'm looking at a 1998 TDi - single owner, - what can I expect issue-wise esp with the Tdi aspect?
  
  thanks
  
  Aivars
• #1 by rallydiesel on 09 Oct, 2010 14:33
• That's probably the best year for the tdi. Very similar to the AAZ but with a bit better mileage and power. A vagcom/VCDS cable is a good investment so you can clear codes and decrease your egr duty cycle.
• #2 by 8v-of-fury on 09 Oct, 2010 21:55
• 1998 is an AHU TDI, the good ones
  
  Its just as simple, if not more so then the AAZ and older ME/MF and CR engines. (ok maybe not as simple as an old 1.6 n/a.. but damn close)
  
  just a bunch of wires and sensors added, to better refine EVERYTHING that goes on with the engine. Perfection if you ask me. The PD motors is where they got greedy.. and changed a whack of stuff, and made it complicated as all hell.. mind you they make a butt-load of power
  
  you will like the AHU, a simple bolt on will net you like 35hp and 74 ft.lbs
• #3 by homerj1 on 10 Oct, 2010 04:07
• Thanks for the info, guys!
  
  A few more questions.
  
  1. Chassis -wise the 98 tdi Jetta is the same as my 96 Golf? Other then engine? ( I've got some 93-97 parts kicking around)
  2. What is the cost\difficulty of changing the timing belt?
  3. Is there anything specific I need to look for when checking out the car? ie: AAZ pulley wobble? Turbo Issues
  4. What is the bolt on that will increase my hp and torque?
  5. How much can I alter stuff using Vag-Com?
  
  thanks again, this is a great forum for help and advice.
  
  just got to convince the wife....
  
  Aivars
• #4 by ricosuave on 10 Oct, 2010 06:31
• 
  1. yes
  2. not too bad ffom what Ive read here
  3. the engine isnt an aaz, so you dont have to worry about that - just a general inspection
  4. nozzle upgrade, I would guess
  5. lots, but its for diagnostic too, a worthwhile investment
  
  
  
  
• #5 by catlin_cava on 10 Oct, 2010 07:42
• I upgraded from running MK3 AAZs to MK4 ALH TDI and its a world of difference I find TDI from IDI(mind you the ALH is damn near impossible to work on when *** breaks) if I could of found a decent shaped MK3 AHU Jetta I would of bought it.
  
  1 power box(250$) will give about 50HP and 70ftlbs of torque, Nozzles are another great upgrade, it will give you about the same power.
  
  TDIs are a blast for power
• #6 by 8v-of-fury on 10 Oct, 2010 09:01
• $700 of bolt ons and you are a rockett ship! lol
• #7 by homerj1 on 10 Oct, 2010 09:21
• Thanks for the help. I'm still sort of sitting on the fence, as my 96 Golf aaz is getting a bit tired - floors, and a host of accumulated small things.
  
  So I was looking for a change - but am sort of unsure of the reliability and  parts price costs when it come to sensors and stuff.
  How much more get up and go and economy can I expect from a AHU?
  
  Also, I've got a pile of aaz diesel stuff, most of which would be useless.
  
  thanks for your help!
  
  Aivars
  
  btw catlin_cava, did you make it home ok - read your alt. issue. Just think you might have made it home without alt - if you had a IDI? 
• #8 by catlin_cava on 10 Oct, 2010 12:32
• Yea we made it, took us 6 hours to change the alt. Its a big job, and if I had an IDI I would of drove it home lol. But the Jetta everything is electric and the alt. Had seized up completly and the motor wasn't turning over anymore.
• #9 by homerj1 on 16 Oct, 2010 09:39
• Hey Folks, Just an update.....
  
  I bought the 98 Jetta tdi - 284,000 km one owner - no real options - good shape, a few small rust spots, will need in the future some minor floor work, new snows - for $1,100
  
  I was having a CEL issue (glow plug temp), wonky fuel gauge and I also thought the vss was gone - BUT, it was just a broken ground wire at the crazy big black plug ( lots of wires) to the right of the injection pump.
  
  Diesel purged it, new fuel filter - and so far it runs great! Still needs a bit of fine tuning (new vac lines, fuel return hoses)
  
  but most of all, I'm impressed with the performance over my aaz.
  
  thanks again for your help.
  
  Aivars
  
  ps So the question is - Should I remove the muffler, resonator or both?
• #10 by catlin_cava on 16 Oct, 2010 10:59
• On my MK4 I removed the cat and I don't have a resinator and she's working pretty good. But I will replace the cat this spring with a highflow one,
  
  I would remove both and just put a flowmaster freeflowing muffler on and you'll be good.