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vwnewton, VW Owner,ASE Master and L1 Advanced
Category: VW
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Experience:  25 years of VW obsession turned into a job, last 15 years as a VW Tech.
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My rialta surges just off idle and at cruise speed 60mph.

Customer Question

My rialta surges just off idle and at cruise speed 60mph. Has no mas air sensor .New distibutor ignition module plugs wires timng belt 2.5l vw . Fuel pressure good . Any thoughts?
JA: How many miles are on the car? Have you had the fuel pressure tested recently?
Customer: 56K fuel presure reads 45psi
JA: What is the model/year of your VW?
Customer: 1996
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: I installed all parts listed in first post
JA: Anything else you think the mechanic should know?
Customer: Thought might be egr unhooked no change
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the VW Mechanic about your situation and then connect you two.
Submitted: 12 months ago.
Category: VW
Customer: replied 12 months ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Wolfgang replied 12 months ago.

Thanks for choosing Just Answer . I'm Wolfgang here to help!!

I am confident we can resolve your problem together. Please
understand that I don't know your skill level. In most cases when you have a problem
with the way the vehicle performs, specialized tooling is required to acquire computer
data/information or engine testing results. We didn’t build these complicated vehicles; we
just diagnose and fix them. Also understand that I can't see, smell, hear, or touch the
vehicle either, so it may take a few replies to get to satisfactory results. I am also going to
direct you with the fastest, easiest and most common things to check first. Please be
patient and permit me to do what I do best.
I also try to give all of the information you may need, expecting a “positive rating” in
return. I will also continue assisting you after you have rated me, if necessary. If there
is any reason I cannot get a positive rating, please let me know why “in advance”, so I
can go another direction for you. I am sorry you’re having this problem; I’ll help you
through it.
Below is my first answer or request for more information. If you do not understand it, or you need more information from me, or need me to go in more detail.

I do need a vin # ***** the vehicle to assist.

Customer: replied 12 months ago.
Vin number is ***** Had it scanned at local shop no codes came up. Not VW expert.
Expert:  Wolfgang replied 12 months ago.

ok i do need you to double check the vin # ***** (pic would be awesome to verify)

what I want you to do is at the battery area is the ecu for the engine and there should be a vacuum hose . replace that vacuum hose and the recheck the running of the vehicle

please let me know

Customer: replied 12 months ago.
Cant get good picture Vin is. 1WVAE07050TH035011 Replaced vacumn hose to ECU runs same .
Customer: replied 12 months ago.
17 inches at idle
Expert:  Wolfgang replied 12 months ago.

where are you located . i need to know elevation level.

Customer: replied 12 months ago.
northern Illinois 650 ft above sea levek
Expert:  Wolfgang replied 12 months ago.

was the surge evident before the timing belt was replaced?

Customer: replied 12 months ago.
Cant say bought it not running , no spark , timing couldnt be set , belt had jumped several teeth.
Expert:  Wolfgang replied 12 months ago.

was a compression test performed and a leak down test . this is an interference motor and if off by several teeth you may have a slight bent valve causing this issue!!

please let me know

Customer: replied 12 months ago.
No, idles perfect smooth and steady
Expert:  Wolfgang replied 11 months ago.

what is the fuel pressure when off idle and cruise when the surge occurs?

Customer: replied 11 months ago.
Fuel pressure at idle 36psi rises to 37-38 off idle .40 at 2200-2500 rpm ,varies about 1lb at these rpms.
Expert:  Wolfgang replied 11 months ago.

what is the fuel pressure when the vacuum is removed from the regulator?

if at 44 psi then i would recommend to remove the grounds and clean and then retorque . most of the grounds are arounf the battery area and chassis frame in that same area. there are some on the block that needs to be checked also.

Customer: replied 11 months ago.
Three grounds at battery, one for coil on body below battery, one lower front center of block,are there any more in engine compartment? How under dash?
Expert:  Wolfgang replied 11 months ago.

the ecu ground is under the hood and need to make sure on that

Customer: replied 11 months ago.
Check all ground I could find ,voltage drop as well,everything still same. Timing seems to very a lot when surge occurs, watching timing mark with light. Now when fully warmed up wants to die out at idle 800rpm or so ,but opens up idle control and does not die. Do ecus ever fail on these?
Expert:  Wolfgang replied 11 months ago.



Customer: replied 11 months ago.
Little or no response when adding fuel in front of throttle body. Tried gas WD40 chokes a little on carb cleaner. Tried to send you a video of it running.
Customer: replied 11 months ago.
What is 4 wire sensor next to 3 wire throttle position sensor? All one unit.
Expert:  Wolfgang replied 11 months ago.

pic of sensor area and sensor please

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